Work out co2 emissions from fuel instantly with clear inputs, formula shown and shareable results.
Burning fuel converts almost all its carbon to carbon dioxide, so emissions per litre are fixed by composition: 2.31 kg for petrol and 2.68 kg for diesel, which is denser and more carbon-rich per litre. Fifty litres of petrol releases 115.5 kg of CO2 - more than the fuel weighed, because each carbon atom collects two oxygens from the air.
Emissions
CO2 = volume x emission factor
Tree offset
a mature broadleaf absorbs roughly 21 kg of CO2 a year
Because the oxygen comes from the atmosphere. Carbon's mass of 12 becomes carbon dioxide's 44, so mass more than triples.
Diesel packs more energy and carbon per litre, but diesel engines are more efficient, so emissions per kilometre are usually lower.