Greenhouse Gas Converter Calculator

The calculator multiplies your methane input by its GWP-100 factor of 27.9 and divides by 1000 to convert kilograms to tonnes, so even a modest 50 kg of methane produces nearly 1.4 tonnes of CO2e — meaning methane at only a fraction of your CO2 tonnage by weight can still represent a meaningful share of total warming impact. This is exactly why the calculator reports a separate 'non-CO2 share' percentage rather than only the total, since mass alone badly understates a gas's true climate effect.

The 20-year values weight short-lived, potent gases far more heavily — methane's GWP nearly triples from 27.9 to 81.2 — because over a shorter time window a gas's own atmospheric lifetime matters more than it does over 100 years. Use the 20-year horizon specifically for near-term climate impact analysis, like short-lived pollutant mitigation planning; standard corporate and national emissions inventories should stick with the 100-year default this calculator ships with.

SF6 carries a GWP-100 of 25,200 and CF4 carries 7,380 — orders of magnitude higher than methane's 27.9 or N2O's 273 — because both are extremely long-lived, potent industrial gases used in things like electrical switchgear and semiconductor manufacturing. A single kilogram of SF6 alone converts to over 25 tonnes of CO2e, so even small leaks of these gases can swamp the CO2e total contributed by hundreds of tonnes of actual CO2.

No — it uses a single GWP-100 value of 27.9 for all methane regardless of source, even though IPCC AR6's Table 7.15 (Working Group I, Chapter 7) separately lists 29.8 for fossil-origin methane to account for additional climate-carbon feedback effects. If your methane emissions are specifically fossil-sourced (like natural gas leaks) rather than biogenic (like livestock or landfills), your true CO2e from methane may run slightly higher than what this calculator reports.