Lifecycle · Cradle-to-Grave
EV vs Petrol & Diesel Lifecycle Carbon Calculator
Compare the whole-life carbon of a battery-electric car against an equivalent petrol or diesel model — manufacturing plus use phase — and find the break-even distance at which the electric car overtakes combustion, under an ISO 14040/44 lifecycle boundary with segment-based energy and charging-grid intensity read from the MasterBrain.
Comparison formula (per powertrain, over a fixed lifetime distance):
Lifecycle emissions = Embodied (manufacturing) emissions + Use-phase emissions per km × Lifetime distance
The calculator computes this total three times — once each for petrol, diesel, and battery-electric — over the same lifetime distance, then reports the break-even distance: the point at which the electric car’s higher manufacturing emissions are repaid by its lower per-kilometre running emissions. Before break-even the combustion car is ahead on cumulative carbon; after it, the electric car is, and stays, ahead.
Two carbon buckets, not one. A tailpipe figure captures only what comes out of the exhaust while driving. A lifecycle comparison adds the emissions embedded in making the car — the body and drivetrain (the “glider”) plus, for an electric car, the battery — and counts the full upstream fuel or electricity chain during use. An electric car starts life with a manufacturing carbon debt, mostly from the battery, and pays it down over the kilometres it drives.
The embodied term. Manufacturing emissions are read from the MasterBrain (vehicle_lca.*, ICCT 2025): a glider figure per powertrain, plus for the electric car a battery figure derived from its capacity in kWh, its chemistry (LFP, NMC622, or NMC811), and the country it was produced in — battery manufacture is electricity-intensive, so a cell made on a coal-heavy grid carries a higher embodied factor than the same cell made on a clean one. End-of-life recycling is already netted into the manufacturing figure; there is no separate end-of-life term.
The use-phase term. Running emissions are per-kilometre. For petrol and diesel the calculator reads a segment-specific tailpipe factor (Scope 1 combustion) and adds the well-to-tank chain (Scope 3 Category 3) that gets fuel from the ground to the pump. For the electric car it reads a segment-specific energy consumption in kWh/km, multiplies by the location-based intensity of the selected charging grid (DEFRA 2026 for the UK, Ember or eGRID elsewhere), and adds transmission-and-distribution losses. You do not type an efficiency figure or a grid intensity — you pick a car segment and a charging country, and the engine reads the rest.
The grid is a static snapshot. Version 1 holds the selected grid’s current carbon intensity constant across the whole vehicle lifetime. It does not model the grid decarbonising over the car’s life, which would make the electric car’s real-world advantage larger than the figure shown. The result is therefore a deliberately conservative, single-vintage comparison — not a forward projection.
Scope of version 1. Petrol, diesel, and battery-electric only. Conventional hybrids (HEV) and plug-in hybrids (PHEV) are excluded because DEFRA does not publish a like-for-like segment factor for them, and the calculator does not fabricate one. GWP basis is AR5 GWP-100 throughout, matching the DEFRA 2026 use-phase factors.
Advanced assumptions — battery, losses, fuel supply
Petrol · diesel · battery-electric compared over the full vehicle lifetime. Use-phase (tailpipe, well-to-tank, EV charging, grid) from DEFRA 2026; manufacturing (vehicle + battery) from ICCT 2025 / GREET with a T&E 2023 + IVL 2019 battery band. Grid-agnostic — the EV recomputes for any charging country. AR5 GWP-100. Reads MasterBrain V3 live.
Choose a segment and charging country, then Compare
Results show the break-even distance, a cumulative-emissions crossover chart, a lifecycle-stage breakdown, grid sensitivity, audit trail and export.
Results are indicative and compare typical, segment-representative vehicles — not specific models. Use-phase factors are DEFRA 2026 (AR5 GWP-100); manufacturing and battery carbon are ICCT 2025 / GREET with a Transport & Environment (2023) and IVL (2019) uncertainty range — battery manufacturing carbon is inherently uncertain and depends heavily on chemistry and where the cells are made. The EV charging result depends entirely on the selected grid. Vehicle production is modelled at medium-segment representative values; maintenance, tyres, road infrastructure and refrigerant are excluded. Hybrid and plug-in hybrid are out of scope in this version. Verify assumptions against your own vehicle, duty cycle and procurement data before using for reporting or procurement decisions.
Every few months a headline claims an electric car has to be driven some improbable distance before it is cleaner than a petrol one — or that the battery is so carbon-intensive the whole premise collapses. Both the alarm and the reassurance usually rest on a single number pulled out of context: a manufacturing figure with no mileage attached, or a tailpipe figure with no factory attached. The honest answer is a comparison, not a number, and it has a shape. An electric car begins life behind on carbon because its battery is expensive to make, and it catches up over distance because it is cheap to run. The only questions that matter are how far behind it starts, how fast it catches up, and what grid it charges on.
This calculator computes the whole-life carbon of a petrol, diesel, and battery-electric car of the same segment over the same lifetime distance, and returns the break-even distance — the kilometre at which the electric car draws level and pulls ahead. It reads segment energy and fuel factors from DEFRA 2026, embodied manufacturing figures from ICCT 2025, and grid intensity for roughly 200 countries, so the same electric car can be tested on a clean grid and a coal-heavy one and the verdict compared.
An electric car’s lifecycle carbon equals its manufacturing emissions (higher than a combustion car’s, mostly because of the battery) plus its running emissions (much lower). The break-even distance is where the running saving repays the manufacturing debt. On the UK grid, a typical mid-size electric car breaks even against petrol at around 22,000 km — under two years of average driving — and finishes its life having emitted roughly two-thirds less carbon. On a very clean grid it breaks even sooner; on a coal-heavy grid it takes far longer and saves far less. The grid decides the verdict.
What a lifecycle comparison measures
A lifecycle comparison measures the total carbon a car is responsible for from the factory to the scrapyard — the emissions embedded in making it, plus the emissions from every kilometre it drives — rather than only what leaves the exhaust pipe. It is the difference between asking “what does this car emit while driving” and “what does choosing this car cost the atmosphere over its life.” For a petrol or diesel car the two answers are close, because most of its carbon is burned in use. For an electric car they are very different, because a large share of its carbon is spent before it is ever driven.
The two carbon buckets — manufacturing and use
Every car’s lifecycle carbon divides into two buckets. The embodied bucket is the one-time emissions of manufacturing: extracting and refining materials, building the body and drivetrain, and — for an electric car — making the battery. The use-phase bucket is the recurring emissions of driving: burning fuel, or generating and delivering the electricity that charges the battery. A combustion car carries a small embodied bucket and a large use-phase bucket. An electric car inverts this — a larger embodied bucket, dominated by the battery, and a much smaller use-phase bucket. Lifecycle accounting is simply the exercise of adding both buckets for each car and comparing the totals over a realistic lifetime distance.
Why the tailpipe number is the wrong number
A tailpipe figure — grams of CO₂ per kilometre from the exhaust — is what vehicle regulations have historically measured, and it is the number most people carry in their heads. It is the wrong basis for comparing an electric car to a combustion one for two reasons. First, it counts only Scope 1 combustion and ignores the well-to-tank emissions of producing and distributing the fuel, which add roughly a quarter again to a combustion car’s running carbon. Second, it reads zero for an electric car, which has no tailpipe — but an electric car’s running emissions are real, they just occur at the power station rather than the exhaust. Comparing a combustion car’s tailpipe against an electric car’s non-existent one is not a comparison at all. A lifecycle boundary fixes both problems by counting the full energy chain for every powertrain and adding manufacturing on top.
Cradle-to-grave boundary — what is in, what is out
- In scope — vehicle manufacture (embodied). The glider: body, chassis, drivetrain, and assembly, expressed as one-time emissions per vehicle from the ICCT 2025 dataset. End-of-life recycling is netted into this figure.
- In scope — battery manufacture (embodied, electric only). Cell and pack production, scaled by capacity, chemistry, and production-country grid intensity.
- In scope — use-phase tailpipe (Scope 1, combustion only). Direct combustion emissions per kilometre, by segment and fuel.
- In scope — use-phase fuel supply (Scope 3 Category 3, combustion). The well-to-tank chain that gets fuel to the pump, included when the fuel-supply option is on.
- In scope — use-phase charging (Scope 2 + T&D, electric). Electricity generated to charge the battery, plus transmission-and-distribution losses.
- Out of scope. Road and charging infrastructure, maintenance and consumables, and the residents’ or driver’s wider lifestyle emissions. A separate end-of-life line is out of scope because recycling is already netted into the manufacturing figure.
How the calculation works
Each powertrain’s lifecycle total is one embodied figure plus a per-kilometre use figure multiplied out over the lifetime distance:
Lifecycle emissions (tCO₂e) = Embodied emissions + (Use-phase emissions per km × Lifetime distance)
The embodied term — glider plus the battery premium
Manufacturing emissions are a one-time figure, read from the MasterBrain rather than entered. For a combustion car it is a single glider figure per powertrain. For an electric car it is the glider figure plus a battery figure — and the battery is where the electric car’s manufacturing premium comes from. The battery figure is the pack’s capacity in kWh multiplied by an emission intensity that depends on the cell chemistry and the country of production. Chemistry matters because LFP, NMC622, and NMC811 cells differ in material and energy intensity; production country matters because making a cell is electricity-hungry, so a battery built on a coal-heavy grid embeds more carbon than the identical battery built on a clean one. A larger battery buys more range at the cost of a heavier manufacturing debt to repay over the vehicle’s life.
The use-phase term — segment energy and the fuel or grid factor
Running emissions are per-kilometre, and here too you select rather than type. Choosing a car segment tells the engine how much energy the car uses per kilometre — a fuel factor in litres-equivalent for combustion, an electricity figure in kWh/km for the electric car — read from the DEFRA 2026 segment tables. For a combustion car the per-kilometre figure is the tailpipe combustion factor (Scope 1) plus, when enabled, the well-to-tank fuel-supply factor (Scope 3 Category 3). For an electric car it is the segment energy consumption multiplied by the selected charging grid’s location-based intensity (Scope 2), scaled up for transmission-and-distribution losses. The Scope 2 electricity factor logic is the same grid dataset used across the platform’s electricity calculators.
The break-even equation — carbon payback distance
The comparison the calculator exists to make is the break-even, or carbon payback, distance: how far the electric car must be driven before its running saving repays its manufacturing debt. It falls straight out of the two lifecycle equations set equal to each other:
Break-even distance = (EmbodiedEV − EmbodiedICE) ÷ (Use-phase per kmICE − Use-phase per kmEV)
The numerator is the electric car’s manufacturing head-start in carbon debt; the denominator is how much less carbon it emits per kilometre. Divide one by the other and you get the distance at which the two cumulative curves cross. Two edge cases fall out of the same equation: if the electric car’s per-kilometre emissions are not lower than the combustion car’s — possible on a very dirty grid — there is no break-even within the vehicle’s life, and the calculator says so rather than reporting a fictitious distance. If the electric car’s manufacturing emissions are already lower than the combustion car’s, it is ahead from the first kilometre.
Break-even distance is the whole comparison in one number. A large battery or a dirty production grid pushes the numerator up and the break-even further out. A clean charging grid or a thirsty combustion comparator pushes the denominator up and the break-even closer in. Every lever that matters — battery size, battery chemistry, production country, charging country, vehicle segment — moves the break-even in a direction you can reason about, which is why the calculator surfaces it as the headline rather than a single lifetime tonnage.
The grid decides the verdict
The single most important input to an electric car’s lifecycle result is the grid it charges on, because the use-phase bucket — the one the electric car is supposed to win on — is electricity multiplied by grid intensity. A clean grid makes that bucket nearly empty; a coal-heavy grid fills it back up. The same electric car, with the same battery and the same manufacturing debt, can break even against petrol in well under two years on one grid and take nearly three on another, and can finish its life having saved three-quarters of its combustion carbon or only a third of it.
Same electric car, three grids, three verdicts
The worked example below runs one identical electric car on the UK, French, and Chinese grids. The manufacturing debt is fixed at 11.1 tonnes in all three cases; only the per-kilometre charging emissions change, because only the grid intensity changes. On the French grid — heavily nuclear and among the cleanest in Europe — charging adds under nine grams per kilometre and the car finishes its life having emitted a fraction of the petrol comparator. On the Chinese grid, still coal-heavy in aggregate, charging adds over a hundred grams per kilometre, the break-even distance nearly doubles, and the lifetime saving shrinks by more than half. Same car, same factory, opposite conclusions — set entirely by where it plugs in.
The calculator holds the selected grid’s current intensity constant for the vehicle’s entire life. Real grids are decarbonising, so an electric car charged on a grid that gets cleaner every year will beat the figure shown — the static-snapshot result is conservative in the electric car’s favour, not optimistic. Do not read the break-even distance as a forecast. It is a snapshot: “if this grid never changed, here is where the electric car draws level.” A forward projection that credited grid decarbonisation would show break-even sooner and lifetime savings larger, and is out of scope for version 1.
Average versus marginal grid intensity
The calculator uses each country’s average location-based grid intensity — the published national or regional figure from DEFRA 2026 for the UK, Ember for most countries, and eGRID for the United States. This is the correct basis for lifecycle carbon accounting and for disclosure. It is worth knowing that the marginal intensity — the emissions of the specific extra generation that responds to charging demand, which depends on time of day and what is on the margin — can differ from the average, and time-of-use charging strategies are built around that gap. Average intensity answers “what is this car’s footprint”; marginal intensity answers “what does charging it now add.” The calculator answers the first question, which is the one lifecycle accounting asks.
Inputs this calculator needs — and where they come from
The calculator is built so that you choose from menus and the engine reads the physics. You do not enter an efficiency figure, a fuel-economy figure, or a grid intensity — those are read from the MasterBrain once you pick a car segment and a charging country. The inputs below are everything the comparison needs.
| Input | What you pick or enter | Default | What the engine reads |
|---|---|---|---|
| Car segment | One of nine DEFRA classes (mini through dual-purpose 4×4) | Lower medium | Segment tailpipe/fuel and electric energy-per-km factors |
| Charging country | Any grid in the MasterBrain (~200) | United Kingdom | Location-based grid intensity for that country |
| Annual mileage | Kilometres per year | 15,000 km/yr | Converts break-even distance into a break-even time |
| Vehicle lifetime | Total lifetime distance in km | 240,000 km | The distance the use phase is multiplied over |
| Battery capacity | kWh (or leave blank for the segment default) | Segment default (58 kWh for lower medium) | Scales the battery embodied figure |
| Battery chemistry | LFP, NMC622, or NMC811 | NMC622 | Selects the battery emission-intensity row |
| Battery production country | EU, USA, Korea, Japan, or China | China | Selects the region multiplier on the battery figure |
| Grid T&D loss | Percentage uplift for transmission and distribution | 10% | Applied to the electric use-phase figure |
| Real-world uplift | Percentage uplift over lab consumption | 0% | Applied to both fuel and electricity use |
| Include fuel well-to-tank | On or off | On | Adds the Scope 3 fuel-supply chain for combustion |
The two inputs that move the result most are the charging country and the battery capacity. The charging country sets how steep the electric car’s use-phase line is — the whole verdict pivots on it. The battery capacity sets how far behind the electric car starts, because it drives the manufacturing debt. If you are testing a single vehicle, get those two right first; annual mileage only rescales distance into time and does not change the break-even distance itself.
Petrol vs diesel vs battery-electric
Version 1 compares three powertrains. Petrol and diesel differ mainly in their use phase — diesel is more energy-dense and typically emits a little less carbon per kilometre than petrol in the same segment, though it starts from a similar manufacturing figure. The battery-electric car inverts the shape entirely: a higher manufacturing figure, a much lower use-phase figure, and a verdict that depends on distance and grid.
| Dimension | Petrol | Diesel | Battery-electric |
|---|---|---|---|
| Manufacturing (embodied) | Lower — glider only | Lower — glider only | Higher — glider plus battery |
| Use phase per km | Highest — tailpipe plus fuel supply | High — slightly below petrol per km | Lowest on a clean grid; can rise above diesel on a dirty grid |
| Dominant carbon bucket | Use phase | Use phase | Manufacturing (on a clean grid) or use phase (on a dirty grid) |
| Key sensitivity | Fuel factor, mileage | Fuel factor, mileage | Charging grid, battery size, battery production country |
| Best-fit case | Low-mileage, short-life use | High-mileage long-distance use | Any grid cleaner than the fuel it replaces, driven past break-even |
Hybrids are deliberately absent from version 1. Conventional hybrids (HEV) and plug-in hybrids (PHEV) sit between combustion and battery-electric, but DEFRA does not publish a like-for-like segment factor for them on the same basis as the three powertrains here, and the calculator does not invent one. A plug-in hybrid in particular is difficult to account honestly because its real-world emissions depend heavily on how often the owner actually charges it rather than running on the engine — a behaviour the vehicle’s rated figure does not capture. Rather than publish a fabricated comparison, version 1 covers only the three powertrains with sound segment factors.
Worked example — break-even at three grid intensities
This example reproduces exactly against the live calculator. It takes one electric car and one combustion pair of the same segment, holds every input fixed except the charging grid, and runs the comparison on three grids of very different carbon intensity — the UK, France, and China — to isolate the one variable that most changes the verdict.
The shared vehicle pair
Every run uses a lower-medium segment car over a 240,000 km lifetime at 15,000 km per year, with a 58 kWh NMC622 battery made in China, a 10% transmission-and-distribution uplift, no real-world uplift, and fuel well-to-tank included. Because the vehicles and the battery are fixed, three figures are constant across all three grids: the petrol car emits 56.4 tonnes over its life (204.92 g/km in use), the diesel car 50.1 tonnes (178.76 g/km), and the electric car carries a fixed 11.1 tonnes of manufacturing debt (6.5 t glider plus 4.64 t battery) before it is driven a single kilometre. Only the electric car’s use-phase emissions — and therefore its lifetime total and its break-even distance — change with the grid.
The three grids, three verdicts
Charging grid intensities used: UK 0.13096, France 0.04144, China 0.52649 kg CO₂e/kWh (location-based). The electric car’s manufacturing debt is 11.1 tonnes in every row; only its charging emissions differ.
| Charging grid | EV use (g/km) | EV lifetime (t) | Break-even vs petrol | Break-even vs diesel | Saving vs petrol |
|---|---|---|---|---|---|
| United Kingdom (0.131) | 27.59 | 17.8 | 22,218 km (~1.5 yr) | 26,063 km | 38.6 t · 68% |
| France (0.041) | 8.73 | 13.2 | 20,082 km (~1.3 yr) | 23,172 km | 43.1 t · 77% |
| China (0.526) | 110.91 | 37.8 | 41,909 km (~2.8 yr) | 58,069 km | 18.6 t · 33% |
Reading the result
Two patterns define the comparison. The first is that the grid moves both the finish line and the starting effort. On the French grid the electric car breaks even against petrol in about 20,000 km and finishes its life having emitted 77% less; on the Chinese grid the same car takes over 40,000 km to break even and saves only 33%. The manufacturing debt never changed — 11.1 tonnes throughout — but the rate at which it is repaid did, because the repayment comes from the use-phase gap and that gap collapses on a dirty grid.
The second is that even on a coal-heavy grid the electric car still wins over its life, just by less and later. The Chinese-grid run breaks even at around 42,000 km — well inside a 240,000 km lifetime — and ends 18.6 tonnes ahead of petrol. The “electric cars never pay back their battery” claim only holds on a grid dirty enough that the per-kilometre emissions are no lower than the combustion car’s, at which point the calculator reports no break-even rather than a distance. On any grid cleaner than the fuel it displaces, the electric car repays its battery and pulls ahead; the grid sets how quickly, not whether.
Carbon payback — the metric that answers the real question
Carbon payback distance — the same quantity as the break-even distance — is the metric a lifecycle comparison exists to produce, because it is the one that answers the question people actually ask: is the electric car worth it, and from when. A lifetime tonnage answers “how much” but hides the shape; a per-kilometre figure answers “how clean to run” but ignores the manufacturing debt. Payback distance combines both into a single, decision-useful number.
What carbon payback means
Carbon payback is the distance at which the cumulative emissions of the electric car — manufacturing plus running so far — equal the cumulative emissions of the combustion car it is being compared with. Before that distance the electric car is behind, carrying manufacturing carbon the combustion car has not yet matched through fuel. After it, the electric car is ahead and the gap widens with every further kilometre. The calculator renders this as two cumulative-emissions curves against distance, with the crossing point marked — the electric car’s line starting higher and rising gently, the combustion car’s starting lower and rising steeply, meeting at the payback distance.
Why it is expressed in distance, not time
Payback is fundamentally a distance, not a time, because the physics is per-kilometre: the running saving accrues with kilometres driven, not with calendar months. The calculator converts distance into an approximate time using the annual-mileage input purely for intuition — 22,000 km is easier to picture as “about eighteen months” — but the underlying quantity is the distance, and a driver who covers twice the average mileage reaches payback in half the time without changing the payback distance at all. This is why annual mileage does not appear in the break-even equation: it rescales the answer into time but does not move the distance.
When comparing two electric cars rather than an electric car against combustion, the same payback logic applies to the battery-size decision. A larger battery adds range but also adds manufacturing debt, pushing payback further out and lowering the lifetime saving. If two variants of the same model differ only in battery size, the smaller battery almost always has the lower lifecycle carbon for a given driving pattern — the extra range of the larger pack is bought with extra embodied carbon that a typical usage profile never repays.
Common myths about EV lifecycle emissions
Lifecycle comparisons attract a particular set of recurring claims, most of which come from taking one bucket in isolation. Each is addressed against the same accounting the calculator uses.
- “The battery cancels out the benefit.” The battery is real manufacturing carbon — it is why the electric car starts behind — but it is a one-time debt repaid over distance, not a recurring cost. In the worked example the battery adds 4.64 tonnes; the running saving repays that and the rest of the manufacturing gap within roughly 22,000 km on the UK grid, then keeps saving for the remaining 218,000 km of the car’s life.
- “There’s a long tailpipe — the emissions just move to the power station.” True, and the calculator counts them: the electric car’s use phase is grid electricity, not zero. The point is that even after counting the power-station emissions in full, the electric car’s per-kilometre carbon is lower than the combustion car’s on any grid cleaner than the fuel it replaces — which is most grids, and an increasing majority as grids decarbonise.
- “EVs are only clean if the grid is clean.” Partly true and the reason the grid is the headline variable, but the threshold is lower than the slogan implies. The electric car does not need a clean grid to win over its life — it needs a grid cleaner than burning the fuel directly, and even the coal-heavy grid in the worked example clears that bar with a lifetime saving of a third.
- “Manufacturing an EV emits more than driving a petrol car for years.” The manufacturing gap is real but bounded — in the worked example it is repaid in months to a couple of years of typical driving, not the decade the claim implies. The confusion comes from comparing the electric car’s total manufacturing against the petrol car’s tailpipe-only running, which omits the petrol car’s own manufacturing and its fuel-supply chain.
Standards and methodology context
The calculator sits on a lifecycle-assessment basis, drawing use-phase factors from DEFRA and embodied factors from a published vehicle-LCA dataset, expressed on a consistent GWP basis.
The EV vs Petrol Lifecycle methodology sets out the break-even derivation, factor sourcing, and grid-intensity assumptions in full.
| Framework | Role in this calculator | Basis |
|---|---|---|
| ISO 14040 / 14044 | The lifecycle-assessment framework. Defines the cradle-to-grave boundary, the split into manufacturing and use phases, and the principle that comparisons use a consistent functional unit. | Methodology standard |
| ISO 14067 | Product carbon footprint standard. Frames a vehicle’s carbon footprint as a product footprint over its life, consistent with the two-bucket accounting used here. | Methodology standard |
| DEFRA 2026 | Source of the segment fuel and electric-energy factors, the UK grid factor, and the well-to-tank fuel-supply factors. | Factor source (AR5 GWP-100) |
| IPCC AR6 | The global-warming-potential reference. Version 1 reports on AR5 GWP-100 to match the DEFRA use-phase factors; AR6 is the concept anchor for the CO₂e basis. | GWP reference |
| Ember · eGRID | Non-UK grid intensity: Ember for most countries, eGRID for the United States, providing the location-based factor for the selected charging country. | Grid factor source |
Data sources, factor versioning, and update transparency
Emission factors used
| Component | Source (MB key) | Basis | GWP basis |
|---|---|---|---|
| Grid electricity (by country) | grid.<iso3>.electricity.location_based | Location-based national/regional average | AR5 GWP-100 |
| Petrol / diesel tailpipe (per segment) | passenger_vehicles.car.segment.<seg>.<petrol|diesel> | Scope 1 combustion, per km | AR5 GWP-100 |
| Fuel combustion + well-to-tank | fuels.gbr.<petrol|diesel>_average_biofuel_blend.litre (+ .wtt.litre) | Pump fuel, combustion and supply chain | AR5 GWP-100 |
| Battery-electric energy use (per segment) | ev_charging.car.segment.<seg>.bev.energy_use_secr | kWh per km | n/a (activity data) |
| Vehicle manufacture (glider) | vehicle_lca.glider.<petrol|diesel|bev>.production_tco2e | One-time, per vehicle (ICCT 2025) | AR5-compatible |
| Battery manufacture | vehicle_lca.battery.<chem>.production_kgco2e_per_kwh.<region> | Per kWh of capacity (ICCT 2025) | AR5-compatible |
The use-phase fuel and grid factors are DEFRA 2026 (UK) and Ember/eGRID (elsewhere); the embodied vehicle and battery factors are ICCT 2025. All are read live from the MasterBrain at calculation time — the calculator maintains no separate factor store. Grid and fuel factors refresh annually, DEFRA each summer for the UK. GWP basis is AR5 GWP-100 throughout, which is why the result panel carries an AR5 badge rather than AR6; the two must not be mixed within one comparison.
Versioning and update transparency
The worked example above was computed against MasterBrain v2026.27 (deployed 6 July 2026), and every result the calculator produces is stamped with the MasterBrain version it was computed against, so a figure produced against one factor vintage and the same figure produced against a later one are distinguishable in any restatement. The grid factor in particular moves year on year — the UK figure fell sharply in the DEFRA 2026 release — so a break-even distance quoted without a version stamp is not reproducible. Because version 1 uses a static grid snapshot, a result reflects the grid as of its stamped MasterBrain version, not a projection forward.
What’s next — from one vehicle to a fleet
This calculator compares individual vehicles. Scaling the same logic to a fleet — a company car list, a leasing book, or a manufacturer’s sold-vehicle population — changes the unit of accounting but not the underlying method.
Fleet decarbonisation
A mixed fleet’s transition carbon is the sum of each vehicle’s lifecycle position, and the break-even logic drives replacement timing: an old combustion car scrapped early wastes its remaining useful life, while one near end-of-life is a cleaner swap. The Fleet Carbon Footprint Calculator aggregates vehicle-level emissions across a whole fleet.
Own-operations mobile combustion
For the combustion vehicles a company operates directly, the tailpipe emissions are Scope 1 mobile combustion. The Scope 1 Mobile Combustion Calculator computes those directly from fuel use, the same DEFRA segment basis this calculator uses for the combustion comparators.
Charging electricity
The electricity a company uses to charge an owned or operated electric fleet is Scope 2. The Scope 2 Electricity Calculator applies the same location-based grid dataset used here, with market-based reporting where energy attribute certificates apply.
Use-phase of sold vehicles
For a manufacturer, the running emissions of the vehicles it sells are downstream Scope 3. The Use of Sold Products Calculator extends the use-phase term here across a full sales population and product lifetime.
The full methodological deep-dive on vehicle lifecycle attribution — the glider and battery embodied basis, the segment energy factors, the well-to-tank treatment, and the break-even derivation — belongs on a paired methodology page (see the flag in the change summary; the slug is not yet live).
Frequently asked questions
It depends on the charging grid, the battery size, and the cars compared — which is why the calculator returns a distance rather than a slogan. In the worked example, a mid-size electric car on the UK grid breaks even against petrol at about 22,000 km, roughly eighteen months of average driving. On a very clean grid it is sooner, around 20,000 km; on a coal-heavy grid it is later, around 42,000 km. In every case break-even falls well within the vehicle’s life, after which the electric car keeps saving carbon for the rest of its distance.
No, but it is why the electric car starts behind. The battery is a one-time manufacturing carbon debt — 4.64 tonnes in the worked example — repaid over distance by the electric car’s much lower running emissions. Once the break-even distance is passed, the electric car is ahead and stays ahead. The “battery makes it worse” claim compares the electric car’s full manufacturing against the petrol car’s tailpipe-only running, which leaves out both the petrol car’s own manufacturing and its fuel-supply emissions.
Yes. The electric car’s use phase is the segment’s energy consumption in kWh per km multiplied by the selected charging grid’s location-based carbon intensity, scaled up for transmission-and-distribution losses. There is no “zero-emission” assumption — the power-station emissions are counted in full. That is exactly why the charging country is the most important input: it sets how much carbon each kilometre of charging carries.
No. Version 1 holds the selected grid’s current intensity constant for the whole vehicle lifetime. Because real grids are decarbonising, this makes the result conservative in the electric car’s favour — an electric car charged on a grid that cleans up over time will beat the figure shown. The break-even distance is a snapshot on today’s grid, not a forward projection. A version that credited grid decarbonisation would show break-even sooner and lifetime savings larger.
Version 1 covers petrol, diesel, and battery-electric only. Conventional hybrids and plug-in hybrids are excluded because DEFRA does not publish a like-for-like segment factor for them on the same basis as the three powertrains here, and the calculator does not fabricate one. Plug-in hybrids are especially hard to account honestly because their real-world emissions depend heavily on how often the owner charges rather than runs on the engine — a behaviour the rated figure does not capture. A sound comparison needs a sound factor, so the option is left out rather than approximated.
No. You pick a car segment from nine DEFRA classes and a charging country, and the engine reads the per-kilometre energy or fuel use and the grid intensity from the MasterBrain. You can override the battery capacity, chemistry, production country, lifetime, mileage, and the loss and real-world uplift percentages, but you never type an efficiency in Wh/km or a fuel economy in litres per 100 km, and you never type a grid intensity.
Usually the opposite. A larger battery adds manufacturing carbon, which pushes the break-even distance further out and lowers the lifetime saving. Range does not reduce emissions; it adds embodied carbon that a typical driving pattern may never repay. For a given usage profile, the smaller battery that still meets the driver’s real range need generally has the lower lifecycle carbon. The calculator lets you test this directly by changing the battery capacity input.
On carbon alone, diesel typically emits slightly less per kilometre than petrol in the same segment because it is more energy-dense, so a diesel car’s lifetime carbon is usually a little lower than an equivalent petrol car’s — 50.1 against 56.4 tonnes in the worked example. Both are well above the battery-electric total on any grid cleaner than the fuel they burn. Note that this calculator accounts carbon only; diesel’s local air-quality pollutants are a separate consideration outside a CO₂e comparison.
It means the electric car’s per-kilometre emissions on the selected grid are not lower than the combustion car’s, so its cumulative carbon never catches up within the vehicle’s life. This only happens on a grid dirty enough that charging emits as much as or more than burning the fuel directly. On any grid cleaner than the displaced fuel, the calculator returns a finite break-even distance instead. Changing the charging country to a cleaner grid is what resolves it.
Because the running saving accrues per kilometre, not per month. The break-even is fundamentally a distance; the calculator converts it into an approximate time using your annual mileage only to make it easier to picture. A driver covering twice the average mileage reaches break-even in half the time but at the same distance. This is why annual mileage does not change the break-even distance — it only rescales that distance into a time.
Methodology notes and limitations
Lifecycle basis. The calculator implements a cradle-to-grave comparison on an ISO 14040/44 basis: manufacturing (embodied) emissions plus use-phase emissions over a fixed lifetime distance, computed identically for each powertrain. Use-phase fuel, energy, and grid factors are DEFRA 2026 (UK) and Ember/eGRID (elsewhere); embodied vehicle and battery factors are ICCT 2025.
Scope of version 1. Petrol, diesel, and battery-electric passenger cars only. Conventional and plug-in hybrids are excluded for want of a like-for-like DEFRA segment factor. Road and charging infrastructure, maintenance, and consumables are out of scope, as is a separate end-of-life term — recycling is netted into the ICCT manufacturing figure.
Static grid snapshot. The selected charging grid’s intensity is held constant across the vehicle’s whole life. Grid decarbonisation over time is not modelled, making the result conservative in the electric car’s favour. The break-even distance is a snapshot on the stamped grid vintage, not a forward projection.
Average grid intensity. The calculator uses each country’s average location-based grid intensity, the correct basis for lifecycle accounting and disclosure. Marginal intensity — relevant to time-of-use charging decisions — is not used.
Segment factors, not vehicle-specific. Energy and fuel use come from DEFRA segment averages, not a specific make and model. A particular car may be more or less efficient than its segment average; the battery capacity, chemistry, and production-country inputs allow the embodied side to be tailored, but the per-kilometre energy is segment-based.
GWP basis. AR5 GWP-100 throughout, matching the DEFRA 2026 use-phase factors. The result panel carries an AR5 badge. AR5 and AR6 values must not be mixed within a single comparison.
Factors read live from the MasterBrain. All factors are read at calculation time from the MasterBrain; the calculator holds no separate factor store. On a data-layer miss the engine shows a warning rather than fabricating a value. The worked example is stamped to MasterBrain v2026.27; a future revaluation of the vehicle-LCA or DEFRA factor rows requires the worked example to be re-confirmed.
No assurance opinion. Results are estimates for comparison and decision support. They are not a certified product carbon footprint and should be treated as segment-level guidance rather than a model-specific or assurance-grade figure.