Methane Emissions

Free Methane Emissions calculator with clear step-by-step results.

About Methane Emissions

Methane cannot be reported as raw mass if you want to compare it with carbon dioxide, because a kilogram of it traps far more heat. The chain is: activity × emission factor gives kilograms of CH₄, capture or flaring removes part of that, and the remainder is multiplied by the global warming potential — 28 over a 100-year horizon in IPCC AR5, or about 84 over 20 years — to express it as CO₂ equivalent.

Formulas

Methane released

CH₄ released = activity × emission factor × (1 − captured share)

CO₂ equivalent

CO₂e = CH₄ released × GWP100

Worked example

With the default values below, Methane Emissions returns Warming Impact of 12.600. Change any input above and every figure here is recalculated in your browser.

Inputs used

Activity levelminimum 0 units: 1,000 units
Methane emission factorminimum 0 kg CH₄/unit: 0.5 kg CH₄/unit
Methane GWP over 100 yearsminimum 1: 28
Captured or flaredaccepts 0–100 %: 10 %

Results

Warming Impact: 12.600 t CO₂e
Methane Released: 450.00 kg CH₄
Warming Impact: 12,600.00 kg CO₂e
Methane Captured or Flared: 50.00 kg CH₄

Step by step

1Values used
2Methane released
3CO₂ equivalent
4Warming Impact= 12.600 t CO₂e
5Methane Released= 450.00 kg CH₄
6Warming Impact= 12,600.00 kg CO₂e
7Methane Captured or Flared= 50.00 kg CH₄

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
Emission factors and GWP values are prescribed by the inventory methodology you report under, and differ between IPCC assessment reports and national guidance. Regulatory reporting requires the applicable official factors.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Emission factors and GWP values are prescribed by the inventory methodology you report under, and differ between IPCC assessment reports and national guidance. Regulatory reporting requires the applicable official factors.

Frequently Asked Questions

Should I use GWP100 of 25, 28 or 30?

It depends on the assessment report your inventory follows: 25 in AR4, 28 in AR5, and around 29.8 for fossil methane in AR6. Use whichever your reporting standard specifies and state it, because the choice changes the answer by up to 20%.

Why is the 20-year GWP so much higher?

Methane has an atmospheric lifetime of roughly 12 years, so most of its warming happens early. Over 20 years its GWP is about 84; averaged over 100 years the same pulse looks weaker. Short-horizon figures are the relevant ones for near-term temperature targets.

Does flaring make methane harmless?

No, but it helps considerably. Combustion converts CH₄ to CO₂, which has roughly a twenty-eighth of the warming effect per molecule of methane destroyed. Real flares are not perfectly efficient, so some methane still escapes.