Carbon Equivalent Calculator

A carbon equivalent calculator expresses the warming influence of different greenhouse gases in one comparable unit: carbon dioxide equivalent, commonly written CO2e. Each gas traps heat differently and remains in the atmosphere for a different period. Global warming potential, or GWP, combines those effects over a selected time horizon. Multiplying the mass of a gas by its GWP gives the mass of carbon dioxide with a comparable integrated warming effect over that period. This calculator uses representative 100-year values from the IPCC Sixth Assessment Report: 1 for carbon dioxide, 27.2 for methane, 273 for nitrous oxide, 1,530 for HFC-134a, and 25,200 for sulfur hexafluoride. For example, 100 kilograms of methane multiplied by 27.2 equals 2,720 kilograms of CO2e. The calculator also divides kilograms by 1,000 to show metric tonnes, the unit commonly used in inventories, environmental product declarations, and sustainability reports. GWP is a comparison factor, not a direct measurement of current temperature change. Published values differ by assessment report, time horizon, climate-carbon feedback treatment, and whether methane is fossil or biogenic. Regulations and reporting programs may mandate factors from a specific source or vintage. An organization preparing a formal inventory should follow the protocol, jurisdiction, and factor table that applies to its reporting year rather than substituting the defaults without review. Accurate CO2e begins with accurate activity and emissions data. Confirm whether an amount is measured gas mass, refrigerant loss, fuel-derived emissions, or an estimate produced by another factor. Keep units consistent and avoid applying a GWP twice to data already reported as CO2e. This tool handles one gas at a time; calculate each gas separately and sum the resulting equivalents for a combined inventory. It does not account for upstream lifecycle emissions, avoided emissions, offsets, uncertainty, or atmospheric chemistry beyond the selected GWP. Use the result for transparent comparison and preliminary assessment, then document the gas, amount, factor source, horizon, and calculation method for auditable reporting.