Convert Any Greenhouse Gas to CO₂e
| kg CO₂ | kg CO₂e |
|---|---|
| 0.5 | 0.5 |
| 1 | 1 |
| 1.5 | 1.5 |
| 2 | 2 |
| 3 | 3 |
| 5 | 5 |
| 10 | 10 |
| 20 | 20 |
| 50 | 50 |
| 100 | 100 |
Each row uses the same factor as the converter above: 1 kg CO₂ = 1 kg CO₂e.
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Every greenhouse gas is converted to carbon-dioxide-equivalent the same way — multiply its mass by its global warming potential (GWP) — but the multiplier is different for each gas, from 1 for CO₂ itself to over 25,000 for sulfur hexafluoride. This converter carries all of the main inventory gases: pick a gas, enter a mass, and it returns the CO₂e using that gas’s GWP, read live from the GreenCalculus MasterBrain, on your choice of the AR6 or AR5 basis.
To convert a greenhouse gas to CO₂e, multiply its mass by its global warming potential (GWP): kg CO₂e = kg gas × GWP. For example, 1 kg of methane = 29.8 kg CO₂e and 1 kg of SF₆ = 24,300 kg CO₂e (IPCC AR6, 100-year). Divide by the GWP to reverse it.
kg CO₂e = kg gas × GWP. Reverse: kg gas = kg CO₂e ÷ GWP. The only thing that changes between gases is the GWP — the exchange rate that expresses each gas’s warming as an equivalent mass of CO₂. CO₂ has a GWP of 1 by definition; every other gas is higher.
Greenhouse gas GWP table (100-year)
The table lists the 100-year global warming potentials this converter uses, on the current IPCC AR6 basis and the earlier AR5 basis. Multiply a mass of any gas by the GWP to get its CO₂e.
| Gas | Also known as | GWP-100 (AR6) | GWP-100 (AR5) |
|---|---|---|---|
| Carbon dioxide | CO₂ | 1 | 1 |
| Methane (fossil) | CH₄ | 29.8 | 28 |
| Methane (biogenic) | CH₄ | 27 | 28 |
| Nitrous oxide | N₂O | 273 | 265 |
| HFC-134a | R-134a | 1,530 | 1,300 |
| HFC-410A | R-410A | 2,256 | 1,923 |
| HFC-32 | R-32 | 771 | 677 |
| HFC-404A | R-404A | 4,728 | 3,943 |
| HFC-23 | — | 14,600 | 12,400 |
| Sulfur hexafluoride | SF₆ | 24,300 | 23,500 |
| Nitrogen trifluoride | NF₃ | 17,400 | 16,100 |
| PFC-14 | CF₄ | 7,380 | 6,630 |
| PFC-116 | C₂F₆ | 12,400 | 11,100 |
| PFC-218 | C₃F₈ | 9,290 | 8,900 |
| PFC-51-14 | C₆F₁₄ | 8,620 | 7,910 |
GWP-100 values from the IPCC (AR6, 2021; AR5, 2013). The converter above reads the AR6 and AR5 figures live from the MasterBrain, so the tool stays current if the IPCC revises them.
How the conversion works
Carbon-dioxide-equivalent is a common currency for greenhouse gases: it restates any gas as the mass of CO₂ that would cause the same warming over a chosen period. The exchange rate is the gas’s global warming potential, which bundles how strongly the gas absorbs heat and how long it survives in the atmosphere.
Why the multiplier varies so much
The GWPs span more than four orders of magnitude. CO₂ is the reference at 1. Methane is short-lived but potent (about 30). Nitrous oxide is long-lived and strong (273). The fluorinated gases — HFCs, PFCs, SF₆ and NF₃ — are extraordinarily persistent and absorb intensely, giving GWPs in the thousands to tens of thousands. That range is why a few kilograms of an F-gas can outweigh tonnes of CO₂ in an inventory.
AR6 vs AR5
The IPCC revises GWP values with each assessment report. AR6 (2021) is the current basis; AR5 (2013) is still used by DEFRA and for pre-2021 historical comparison. The differences are modest for most gases but real, so an inventory should state which assessment it uses and apply it consistently — the converter’s vintage selector switches between them for whichever gas you have selected.
Do not mix bases within one total. A CO₂e figure only adds up if every gas in it was converted on the same assessment report (AR6 or AR5) and the same 100-year horizon. Converting methane on AR6 and refrigerants on AR5 in the same inventory produces a number that looks plausible but is not coherent.
The greenhouse gases, grouped
The gases in the converter are the ones inventories actually report, in four families:
- CO₂, methane and nitrous oxide — the three dominant gases, covered by dedicated converters for methane and nitrous oxide.
- Hydrofluorocarbons (HFCs) — refrigerants such as R-134a, R-410A, R-32 and R-404A, plus HFC-23 from industry.
- Perfluorocarbons (PFCs) — CF₄, C₂F₆ and their relatives, mainly from aluminium and semiconductor manufacture.
- SF₆ and NF₃ — the highest-GWP gases, from electrical switchgear and electronics manufacture.
Together these are the greenhouse gases counted under the GHG Protocol and the Kyoto framework; the general method for converting any of them is the GWP unit conversion methodology.
Where a multi-gas conversion is used
- Whole-inventory roll-ups. Combining CO₂ from combustion, methane from waste, N₂O from agriculture and F-gases from cooling into one CO₂e total — the step every corporate and national inventory performs.
- Fluorinated-gas accounting. A facility converting a mix of refrigerants and process gases — see the F-gas inventory aggregator and the refrigerant leakage calculator.
- Quick reference. Looking up any gas’s GWP or spot-converting a figure without opening a full inventory tool.
Always record the gas, the assessment report (AR6/AR5) and the horizon (100-year) alongside the number. “10 kg SF₆ = 252,000 kg CO₂e (AR6, GWP-100)” is auditable; “252,000 kg CO₂e” alone is not, because the reader cannot tell which gas or basis produced it.
Frequently Asked Questions
Multiply the mass of the gas by its global warming potential (GWP): kg CO₂e = kg gas × GWP. Each gas has its own GWP — 1 for CO₂, about 30 for methane, 273 for nitrous oxide, and thousands for the fluorinated gases. Pick the gas in the converter above and it applies the right value.
GWP is the amount of warming a gas causes over a chosen period (usually 100 years) relative to the same mass of CO₂. It combines how strongly the gas traps heat with how long it lasts in the atmosphere. Multiplying a gas’s mass by its GWP gives its CO₂-equivalent — the mass of CO₂ that would warm the planet by the same amount.
The main inventory gases: carbon dioxide, methane (fossil and biogenic), nitrous oxide, the common HFC refrigerants (R-134a, R-410A, R-32, R-404A) and HFC-23, the perfluorocarbons (CF₄, C₂F₆, C₃F₈, C₆F₁₄), and sulfur hexafluoride (SF₆) and nitrogen trifluoride (NF₃). These are the gases counted under the GHG Protocol and Kyoto framework.
Of the gases here, sulfur hexafluoride (SF₆) is the highest at 24,300 (AR6, 100-year), followed by nitrogen trifluoride (NF₃) at 17,400 and HFC-23 at 14,600. These extreme values are why even small quantities of these gases matter enormously in an inventory.
Use AR6 (2021) — it is the current IPCC basis — unless you are following AR5 for DEFRA reporting or historical comparison. Whichever you choose, apply it to every gas in the inventory; do not mix AR6 and AR5 in one total. The converter’s vintage selector switches the basis for the selected gas.
For carbon dioxide, yes — its GWP is 1, so 1 kg CO₂ = 1 kg CO₂e. For every other gas they differ: the CO₂e is the mass multiplied by that gas’s GWP, so it is larger than the gas’s own mass. CO₂-equivalent is the common unit that lets different gases be added together.
Divide the CO₂e figure by that gas’s GWP. For example, 243,000 kg CO₂e of SF₆ ÷ 24,300 = 10 kg SF₆. Select the gas and switch the converter’s direction and it does this for you — using the same GWP the CO₂e figure was built with.
Yes, but this converter uses the 100-year horizon (GWP-100), the reporting standard. On a 20-year horizon short-lived gases like methane have much higher GWPs, while long-lived gases such as N₂O and SF₆ change little. A 20-year figure answers a near-term question and should not be mixed into a 100-year inventory total.