How we calculate equivalent kilometres.
A kilogram of CO₂ is hard to picture, so every footprint is also shown as the distance you would need to drive to emit the same amount - something almost everyone has a feel for.
kg CO₂e of product÷kg CO₂e per km=Equivalent km
The car that we use
We use the 2020 Toyota Corolla Sedan (2.0 L, 4 cylinder, automatic, regular petrol). US EPA data gives it 317 g CO₂e per mile, including upstream fuel emissions.
317 ÷ 1000 = 0.317 kg per mile, × 0.621371 miles per km = 0.196974607 kg CO₂e per km.
kg CO₂e of product÷0.196974607=Equivalent km
Why this car
The Corolla is often called the most popular car in the world, so it is a familiar reference almost everywhere. Some cars emit more and some less - see the Cars category for the range.
Volume of CO₂ gas
CO₂ gas weighs about 1.832 kg per cubic metre at room temperature, so the volume shown on each item is its footprint divided by that density.
kg CO₂e of product÷1.832=m³ of CO₂ gas