Convert CO2(e)/kWh to /MWh
Electricity emission factors are published in two units that differ by exactly a thousand — kilograms of CO2e per kilowatt-hour (kg CO2e/kWh) and per megawatt-hour (kg CO2e/MWh) — and the direction of the ×1,000 catches people out. Because a megawatt-hour is 1,000 kilowatt-hours, the per-MWh figure is larger, not smaller: you multiply by 1,000. This converter handles both directions, and the sections below explain the trap, the equivalent units (g/kWh, t/MWh, lb/MWh), and where each form shows up in grid data and Scope 2 reporting.
To convert an emission factor from kg CO2e/kWh to kg CO2e/MWh, multiply by 1,000 (1 MWh = 1,000 kWh): 0.2 kg CO2e/kWh = 200 kg CO2e/MWh. To reverse, divide by 1,000. Note it is ×1,000, not ÷ — the larger energy denominator carries proportionally more emissions.
A site’s location-based grid electricity emission factor is 0.2 kg CO2e/kWh. Expressed per megawatt-hour:
| Step | Calculation | Result |
|---|---|---|
| Factor per kWh | — | 0.2 kg CO2e/kWh |
| Multiply by 1,000 | 0.2 × 1,000 | 200 kg CO2e/MWh |
The same factor read as “0.2 kg CO2e/MWh” instead of per kWh would understate grid intensity a thousandfold.
How to convert CO2(e)/kWh to CO2(e)/MWh
An emission factor is emissions divided by energy. Keeping the emissions the same but making the energy denominator 1,000 times larger (from one kilowatt-hour to one megawatt-hour) means the factor covers 1,000 times as much electricity — so it carries 1,000 times the emissions. The multiplier is the SI step between kilo- and mega-, and it is exact.
The formula
kg CO2e/MWh = kg CO2e/kWh × 1,000
The scaling is molecule-agnostic — it applies identically whether the factor is CO2 only or full CO2e (including CH4 and N2O) — and mass-unit-agnostic: g/kWh → g/MWh is also ×1,000. Only the energy denominator changes.
Converting back: CO2(e)/MWh to CO2(e)/kWh
To go from a per-MWh factor back to per kWh, divide by 1,000. Use the swap control on the converter above to switch direction.
kg CO2e/kWh = kg CO2e/MWh ÷ 1,000
kg CO2e/kWh to kg CO2e/MWh conversion table
Typical grid emission factors span roughly 0.02 (near-zero-carbon grids) to over 0.8 kg CO2e/kWh (coal-heavy grids). The forward column applies ×1,000; the reverse table applies ÷1,000.
| kg CO2e/kWh | × 1,000 | kg CO2e/MWh |
|---|---|---|
| 0.05 | × 1,000 | 50 |
| 0.1 | × 1,000 | 100 |
| 0.2 | × 1,000 | 200 |
| 0.3 | × 1,000 | 300 |
| 0.4 | × 1,000 | 400 |
| 0.5 | × 1,000 | 500 |
| 0.8 | × 1,000 | 800 |
| 1 | × 1,000 | 1,000 |
| kg CO2e/MWh | ÷ 1,000 | kg CO2e/kWh |
|---|---|---|
| 50 | ÷ 1,000 | 0.05 |
| 100 | ÷ 1,000 | 0.1 |
| 250 | ÷ 1,000 | 0.25 |
| 500 | ÷ 1,000 | 0.5 |
| 1,000 | ÷ 1,000 | 1 |
Why per-kWh vs per-MWh matters for grid emission factors
Grid intensity is one of the most-reused numbers in carbon accounting — it drives every location-based Scope 2 figure — yet it is quoted in at least five different unit combinations across DEFRA, Ember, the IEA and the US EPA. Reconciling them is where the ×1,000 error creeps in.
The instinct from mass conversions (kilograms to tonnes is ÷1,000) is backwards here. A per-MWh factor is bigger than the per-kWh factor because the energy denominator grew 1,000×. Dividing when you should multiply turns a realistic 0.4 kg CO2e/kWh into a nonsensical 0.0004 kg CO2e/MWh — a factor-of-a-million slip once compounded. Always sanity-check: a grid factor per MWh should land in the hundreds, per kWh in the tenths.
g/kWh, kg/MWh and t/MWh — the same number in disguise
Two conversions coincide at ×1,000, so some units are numerically identical. A single factor of 0.2 kg CO2e/kWh is the same number as 200 g CO2e/kWh and 200 kg CO2e/MWh; and 0.2 t CO2e/MWh equals 0.2 kg CO2e/kWh. So g CO2e/kWh and kg CO2e/MWh always share the same figure, as do t CO2e/MWh and kg CO2e/kWh.
| Unit | Same factor |
|---|---|
| kg CO2e/kWh | 0.2 |
| g CO2e/kWh | 200 |
| kg CO2e/MWh | 200 |
| t CO2e/MWh | 0.2 |
| lb CO2e/MWh | ≈ 441 |
US grids: pounds per MWh
US datasets — chiefly the EPA’s eGRID — quote grid factors in pounds of CO2 per MWh (typically 600–1,000 lb/MWh), not kilograms. That crosses both a unit system and an energy basis, so it needs its own conversion: see the kg CO2e/kWh to lb/MWh converter. Never compare a bare “450” against a European “0.2” without first resolving the unit — one is lb/MWh, the other kg/kWh.
Where kg CO2e/kWh and /MWh are used: data sources and reporting
Knowing which unit a dataset uses is essential before combining grid factors with consumption data:
- DEFRA UK conversion factors — publish the UK grid factor and most others in kg CO2e/kWh, the standard input for UK SECR and corporate inventories.
- Ember yearly electricity data — reports national and global grid intensity, commonly in g CO2/kWh or kg CO2/MWh (the same number).
- IEA — energy and electricity statistics frequently use g CO2/kWh.
- US EPA eGRID — subregional and national output emission rates in lb CO2/MWh.
- GHG Protocol Scope 2 — grid factors feed both location-based and market-based electricity emissions; report the basis and unit alongside every figure.
Working out the actual emissions from a site’s electricity use — factor × kWh consumed, location- and market-based — rather than just converting the factor’s units?
Frequently Asked Questions
Multiply by 1,000, because 1 MWh = 1,000 kWh. For example, 0.25 kg CO2e/kWh × 1,000 = 250 kg CO2e/MWh. The emissions are unchanged; the energy denominator is 1,000 times larger, so the factor is 1,000 times larger.
Because an emission factor is emissions per unit of energy, and a megawatt-hour is 1,000 times more energy than a kilowatt-hour. The same intensity applied over 1,000× the energy carries 1,000× the emissions, so the per-MWh figure is larger. This is the opposite of mass conversions (kg to tonnes divides by 1,000), which is why it trips people up.
Yes — numerically identical. Going from kg to g multiplies by 1,000, and going from per-kWh to per-MWh also multiplies by 1,000, so 0.2 kg CO2e/kWh = 200 g CO2e/kWh = 200 kg CO2e/MWh. Likewise, t CO2e/MWh equals kg CO2e/kWh.
Divide by 1,000. For example, 500 kg CO2e/MWh ÷ 1,000 = 0.5 kg CO2e/kWh. Use the swap control on the converter to switch direction.
It varies widely by country and year with the generation mix. Low-carbon grids (high renewables or nuclear) can sit below 0.05 kg CO2e/kWh (50 kg/MWh), while coal-heavy grids exceed 0.8 kg CO2e/kWh (800 kg/MWh). Always use the specific published factor for your country and reporting year rather than a generic value.
No. The ×1,000 is a pure unit change on the energy denominator, so it applies identically to a CO2-only factor and a full CO2e factor. Just keep the numerator basis consistent — don’t convert a CO2-only factor and then compare it against a CO2e one.
US EPA eGRID publishes grid factors in pounds of CO2 per MWh, which crosses both the mass unit (lb vs kg) and, relative to a per-kWh figure, the energy basis. Convert those with the dedicated kg CO2e/kWh to lb/MWh converter rather than this one, which stays within metric mass units.