Scope 1 Fuel Combustion Calculators
Scope 1 combustion is the simplest part of an inventory: you burnt it, you own it. The rule holds for every fuel on this page except two — and both exceptions are on this page.
Biomass reports twice. Upstream fuel isn’t yours at all.
Scope 1 fuel combustion covers fuel you burn in assets you own or control — boilers, gensets, CHP, ships and aircraft. Multiply fuel consumed by its DEFRA factor. Biomass splits into an in-scope and a biogenic line; upstream fuel is Scope 3.
Every factor on this page resolves live from the current DEFRA dataset rather than being typed in — so it moves when DEFRA republishes. See how the numbers are built for the vintage and GWP basis.
Start here: pick your fuel source
Stationary combustion calculator
Boilers, furnaces, gensets, process heat. Natural gas, diesel, gas oil, LPG, coal. The default starting point for most Scope 1 inventories.
Biomass & biofuel calculator
Wood pellets, chips, logs, biogas, biodiesel, bioethanol. Produces the two-line report the GHG Protocol requires — in-scope and biogenic memo.
Marine & aviation fuel calculator
Fuel burnt in ships and aircraft you own or control. Scope 1, not business travel — the asset decides, not the journey.
CHP / cogeneration calculator
One fuel input, two useful outputs. Allocates combined heat and power emissions between the heat and the electricity.
Well-to-tank calculator
The upstream emissions of producing and delivering the fuel you burnt. Scope 3 Category 3 — the companion to every calculator above.
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What counts as Scope 1 combustion
The test is ownership of the combustion, not ownership of the fuel or the emissions it eventually causes. That single distinction resolves most of the boundary questions on this page — and the two it doesn’t resolve are the two worth understanding.
The boundary: what you burn vs what you buy
If the fuel combusts inside an asset you own or control, the emissions are Scope 1. A gas boiler in your building, a diesel genset on your site, a vessel in your fleet — all Scope 1, regardless of where the fuel came from or who supplied it. Buy electricity instead and the combustion happened at a power station you do not control, which makes it Scope 2. The physical act of burning is what the scope boundary tracks.
This is why the calculation itself is unglamorous: fuel consumed multiplied by an emission factor. Natural gas at 2.02633 kg [GreenCalculus fuels.gbr.natural_gas.m3 · DEFRA 2026 'Fuels'!D40 · v2026.193] CO₂e per kWh, diesel at 2.58354 kg CO₂e per litre [GreenCalculus fuels.gbr.diesel_average_biofuel_blend.litre · DEFRA 2026 'Fuels'!D72], LPG at 1.55713 per litre [GreenCalculus fuels.gbr.lpg.litre · DEFRA 2026 'Fuels'!D36], coal (industrial) at 2415.03994 per tonne [GreenCalculus fuels.gbr.coal_industrial.tonne · DEFRA 2026 'Fuels'!D131]. The arithmetic is not where inventories go wrong. The boundary is.
Biomass breaks the rule — the two-line report
Burn wood pellets and you have combusted fuel in an asset you control, so the rule says Scope 1. But the CO₂ released was absorbed by the tree during growth, so counting it as a net addition to the atmosphere would double-count against the land-sector accounting that recorded the uptake. The GHG Protocol’s answer is not to exclude it and not to include it, but to split it: the CH₄ and N₂O from combustion are reported in Scope 1, and the biogenic CO₂ is reported as a memo item outside the scopes.
Never net biogenic CO₂ into your Scope 1 total, and never drop it. Both are wrong in opposite directions. Wood pellets carry an in-scope figure of 57.25249 kg CO₂e per tonne [GreenCalculus fuels.gbr.bio.wood_pellets.tonne · DEFRA 2026 'Bioenergy'!D67] and a biogenic memo of 1677.18 kg CO₂ per tonne [GreenCalculus fuels.gbr.biomass.biogenic.wood_pellets.tonne · DEFRA 2026 'Outside of scopes'!D78] — roughly thirty times larger. Reporting only the first understates the stack; adding them together misstates your Scope 1.
Well-to-tank is Scope 3, and it belongs here anyway
Every litre you burn had to be extracted, refined and delivered before it reached you, and those emissions are real. They are also not yours in Scope 1 terms — the combustion happened in someone else’s refinery and someone else’s tanker. The GHG Protocol places them in Scope 3 Category 3, fuel- and energy-related activities.
They sit on this page because they are computed from the same activity data. The well-to-tank figure for your diesel is a function of the diesel you already counted, so the two calculations are one workflow with two outputs landing in two different scopes. Treating them as separate exercises is how Category 3 ends up omitted.
| Source | Scope | Factor basis | What decides it | Methodology | Next step |
|---|---|---|---|---|---|
| Stationary combustion | Scope 1 | Per litre, kWh or tonne of fuel | You own or control the equipment | Fuel combustion methodology | Stationary calculator |
| Biomass & biofuel | Scope 1 (CH₄+N₂O) and outside scopes (biogenic CO₂) | Two rows per fuel — in-scope and memo | The carbon was biogenic in origin | Biomass & biofuel methodology | Biomass calculator |
| Marine & aviation (own ops) | Scope 1 | Per litre of marine or aviation fuel | You own or control the vessel or aircraft | Marine & aviation fuel methodology | Marine & aviation calculator |
| CHP / cogeneration | Scope 1 | Fuel input, allocated across two outputs | One combustion, two products | CHP allocation methodology | CHP calculator |
| Well-to-tank | Scope 3 Cat 3 | Upstream companion to each fuel factor | Combustion happened upstream, not by you | Well-to-tank methodology | Well-to-tank calculator |
What each calculator covers
Stationary combustion — the inventory’s foundation
This is where most Scope 1 inventories start and where most of the tonnage sits: boilers, furnaces, process heat, standby gensets. What drives the workload is not the calculation but the metering — a site with sub-metered gas by building produces a defensible figure quickly, while a site with one supplier invoice and several tenants does not.
The calculator handles the core DEFRA fuel set on the unit basis your data actually arrives in: natural gas per kWh (gross calorific value, matching how UK gas bills are stated), liquid fuels per litre, solid fuels per tonne. Gas oil — red diesel — is worth calling out at 2.75541 kg CO₂e per litre [GreenCalculus fuels.gbr.gas_oil.litre · DEFRA 2026 'Fuels'!D84], because sites frequently record it as “diesel” and pick up the wrong factor. Full method: natural gas, diesel, LPG and coal combustion methodologies.
Biomass & biofuel — the calculator that returns two numbers
The biomass calculator exists because the output shape is different, not because the arithmetic is harder. Every other calculator on this page returns one figure; this one returns two, and a report that shows only one is incomplete regardless of which one it shows.
It covers the solid fuels (wood pellets, chips, logs, grass and straw), the gaseous ones (biogas, landfill gas) and the liquid biofuels (biodiesel, bioethanol, biomethane, biopropane), each with its in-scope CH₄+N₂O row and its biogenic CO₂ memo. One practical note: DEFRA does not publish a per-gas decomposition on its bioenergy data, so unlike the fossil fuels these rows cannot be broken into CO₂, CH₄ and N₂O components — the in-scope figure arrives pre-combined. Full method: biomass and biofuel combustion methodology.
Marine & aviation fuel (own operations) — the asset decides, not the journey
The recurring error here is scope, not factor selection. Fuel burnt in a ship or aircraft your organisation owns or controls is Scope 1 combustion — identical in principle to a boiler, just mobile. Fuel burnt on a flight your employee booked with an airline is Scope 3 Category 6, business travel. Same kerosene, same physics, different scope, because the boundary tracks who controls the combustion.
The calculator covers the marine and aviation fuel set: aviation turbine fuel at 2.54269 kg CO₂e per litre [GreenCalculus fuels.gbr.aviation_turbine_fuel.litre · DEFRA 2026 'Fuels'!D64], aviation spirit for piston aircraft, marine gas oil at 2.77139 per litre [GreenCalculus mobile_combustion.marine_gas_oil.per_litre · DEFRA 2026 'Fuels'!D120] and marine fuel oil for larger vessels. Use it for owned fleet; use business travel calculators for tickets you bought. Full method: marine and aviation fuel (own operations) methodology.
CHP / cogeneration — one fuel, two outputs, one allocation argument
A CHP unit burns one stream of fuel and produces both heat and electricity, which means its emissions have to be divided between two outputs that are not physically separable. There is no measurement that settles this — it is an allocation choice, and different defensible methods give materially different answers for the same plant.
That makes CHP the one calculator in this slice where the method matters more than the data. The efficiency-based approach splits on the useful energy in each output; other approaches weight by exergy or by what the alternatives would have emitted. The calculator implements the allocation and shows the split; the choice of basis is yours to state and to keep consistent year on year. Where CHP output is sold or exported, the boundary question follows the allocation. Full method: CHP cogeneration allocation methodology.
Well-to-tank — the Scope 3 line your Scope 1 data already contains
Well-to-tank takes the fuel volumes you have already assembled for the calculators above and returns their upstream footprint. Nothing new is measured; the same litres are multiplied by a different factor set. That is why it belongs in this slice despite being Scope 3 — the marginal cost of producing the number is close to zero once the Scope 1 work is done.
What it is not is optional-by-default. Category 3 is a required Scope 3 category where fuel use is material, and for most organisations with significant combustion it is material. The honest reason it gets skipped is that it lands in a different part of the report from the data that produces it. Full method: well-to-tank methodology.
The biogenic split: why your wood-pellet boiler reports twice
“Biomass is carbon neutral” is a claim about the carbon cycle, not an instruction about your inventory. The inventory rule is more specific and more useful.
The reasoning runs like this. A tree absorbs CO₂ as it grows. Burn its wood and that CO₂ returns to the atmosphere — the same carbon, completing a cycle rather than adding to the stock. Land-sector accounting already recorded the uptake, so recording the release in your Scope 1 total as well would count the same carbon twice across the two systems. Hence the memo treatment: the biogenic CO₂ is disclosed, prominently and separately, but outside the scope totals.
What the cycle argument does not cover is the rest of the combustion. Burning wood produces CH₄ and N₂O alongside the CO₂, and those are not part of any absorption cycle — they are new warming agents released by your equipment. They stay in Scope 1, which is why a biomass boiler has a non-zero Scope 1 figure rather than a zero one.
The neutrality claim also assumes the biomass was sustainably sourced and regrown. A pellet from a managed forest that is replanted and a pellet from a cleared forest that is not have identical combustion chemistry and very different atmospheric consequences — a distinction your emission factor cannot see. The factor computes the stack; sourcing is a separate question with separate evidence.
Practically, the two-line report is the deliverable: an in-scope figure inside your Scope 1 total, and a biogenic CO₂ memo alongside it. For wood pellets that is 57.25249 kg CO₂e per tonne [GreenCalculus fuels.gbr.bio.wood_pellets.tonne] in scope against 1677.18 kg CO₂ per tonne [GreenCalculus fuels.gbr.biomass.biogenic.wood_pellets.tonne] as memo. A reader seeing only the first would badly underestimate the stack; a reader seeing them summed would think your Scope 1 was thirty times its real size.
How the numbers are built
Every factor on this page resolves live from the same versioned MasterBrain rows the calculators read at runtime — the values above are not typed in, they are fetched, so they move when the dataset moves. You can inspect the source data and its versioning at MasterBrain.
The dataset is DEFRA’s 2026 conversion factors, published for UK reporting and used here for every fuel row. Each factor carries its source cell reference back to the DEFRA workbook, which is what makes an auditor’s trace from your figure to the government publication a single step rather than an investigation. The IPCC 2006 Guidelines supply the underlying stationary-combustion methodology that DEFRA’s national dataset implements, and the GHG Protocol’s Scope 1 stationary combustion guidance governs how the results enter your inventory.
One thing worth stating plainly, because it surprises readers arriving from a disclosure page: DEFRA’s 2026 factors use IPCC AR5 100-year global warming potentials, which is the UK regulatory basis and aligns with SECR reporting. Disclosure frameworks increasingly reference AR6 instead. For combustion the practical difference is small — CO₂ dominates the total and its GWP is 1 under both — so the divergence shows up only in the CH₄ and N₂O slice of the figure. If a DEFRA-based number and an AR6-based number disagree slightly for the same fuel, that is the reason, and neither is wrong.
The honest limitation: a fuel factor is an average for a fuel grade, not a measurement of your combustion. A well-tuned condensing boiler and a neglected one burning the same gas produce the same computed figure. Factors are the right tool for an inventory and the wrong tool for judging equipment.
Zoom out: purchased energy and the rest
This slice covers combustion you own. The larger half of most energy inventories is energy you buy — purchased electricity, where the location-based and market-based methods can give very different answers to the same question; district heating and purchased steam; renewable procurement through RECs, PPAs and residual mix accounting; and the transmission and distribution losses that accompany bought power the way well-to-tank accompanies burnt fuel.
All of that sits on the energy and fuel combustion hub, which covers both halves and is the right starting point if your question is about power you purchase rather than fuel you burn. Most organisations need both: a boiler and a meter, reported under different scopes with different rules.
Purchased electricity, heat and steam have their own slice: the Scope 2 purchased energy hub.
Next step
If you are building a first inventory, start with stationary combustion — it is usually the largest Scope 1 source and the data is already on your invoices. If you burn biomass, use the biomass calculator rather than the stationary one, because the output shape differs. And once your fuel volumes are assembled, run well-to-tank on the same data: it is the cheapest Scope 3 category you will ever complete.
Start with the fuel that dominates your site.
Frequently asked questions
Multiply your gas consumption in kWh by 2.02633 kg CO₂e per kWh [GreenCalculus fuels.gbr.natural_gas.m3] (DEFRA 2026). The one thing to check is the calorific basis: UK gas bills state consumption on a gross calorific value basis, which is what this factor assumes. If your data is on a net CV basis — common in engineering systems and non-UK datasets — you need the net CV factor instead, or the result will be understated by roughly a tenth.
Not in your inventory, no. The biogenic CO₂ is reported as a memo item outside your scope totals rather than excluded — the GHG Protocol requires you to disclose it, just not to add it to Scope 1. And the combustion’s CH₄ and N₂O stay in Scope 1, because those aren’t part of the absorption cycle. So a wood-pellet boiler has a real Scope 1 figure and a much larger biogenic memo beside it. The neutrality claim also assumes sustainable sourcing and regrowth, which an emission factor cannot verify.
Yes, where fuel use is material — which it is for most organisations with significant combustion. Well-to-tank is Scope 3 Category 3, a required category rather than an optional one, and it uses the fuel volumes you have already assembled for your Scope 1 calculation. The marginal effort is near zero once the Scope 1 work is done. What it isn’t is part of your Scope 1 total: reporting it there would double-count against the supplier’s own inventory.
By allocation, not by measurement — the two outputs come from one combustion and cannot be physically separated. The efficiency-based approach splits on the useful energy delivered in each output; other defensible methods weight by exergy or by the emissions each output would have caused if produced separately. They give different answers for the same plant, so the choice matters, needs stating in your methodology, and should stay consistent year on year.
Scope 1, if you own or control the vessel or aircraft. The boundary follows control of the combustion, not the nature of the journey — fuel burnt in your own aircraft is Scope 1 for the same reason fuel burnt in your own boiler is. If instead your employee flew on a commercial ticket, that’s Scope 3 Category 6 business travel: same fuel, different scope, because an airline controlled the combustion.
AR5. DEFRA’s 2026 conversion factors embed IPCC AR5 100-year global warming potentials, which is the UK regulatory basis and aligns with SECR. Disclosure frameworks increasingly reference AR6, so a figure from this page and a figure from an AR6-based tool can differ slightly for the same fuel. For combustion the gap is small: CO₂ dominates the total and has a GWP of 1 under both, so only the CH₄ and N₂O portion shifts. Neither number is wrong — state which basis you used.