Almost all the carbon in fuel becomes CO₂ when burned, so emissions are proportional to fuel used. Cutting fuel use is the most direct way to cut driving emissions.
How to use it
Enter distance, your car’s fuel economy and the fuel type. For a yearly footprint, enter your annual mileage.
What is not included
This covers tailpipe CO₂ only. Fuel production, other greenhouse gases and vehicle manufacturing add more. The tree comparison is only a rough illustration.
Inputs explained
| Field | What to enter |
|---|---|
| Distance driven | Units: km, mi |
| Fuel economy | Units: km/L, mpg (US), mpg (UK) |
| Fuel type | Choose one: Gasoline / petrol, Diesel |
What each result means
- Fuel burned = [Distance driven] ÷ [Fuel economy]
- CO₂ emitted = [Fuel burned] × [Fuel type]
- Tree-years to absorb (≈) = [CO₂ emitted] ÷ 21
Example values
How the main result changes when Distance driven changes and everything else stays at the example values above:
| Distance driven (km) | CO₂ emitted (kg) |
|---|---|
| 500 | 83.9 |
| 750 | 125.8 |
| 1,000 | 167.7 |
| 1,250 | 209.6 |
| 1,500 | 251.6 |
| 2,000 | 335.4 |
Formula
Fuel = distance ÷ fuel economyCO₂ = fuel × emission factor (2.348 kg/L gasoline, 2.689 kg/L diesel)Worked example
1,000 km at 14 km/L on gasoline.
Fuel = 1,000 ÷ 14 ≈ 71.4 L. CO₂ = 71.43 × 2.348 ≈ 167.7 kg.
Key terms
- Emission factor
- Mass of CO₂ released per unit of fuel burned.
- Tailpipe emissions
- Gases leaving the exhaust while driving.
- CO₂e
- Carbon dioxide equivalent, including other greenhouse gases.
Frequently asked questions
Why does diesel emit more per litre?
Diesel contains more carbon per litre, though diesel cars often use fewer litres.
How do I reduce emissions?
Drive less, combine trips, keep tyres inflated and choose efficient vehicles.
Are electric cars zero-emission?
No tailpipe CO₂, but electricity generation may produce emissions.
What formula does the Car CO₂ Emissions Calculator use?
Fuel = distance ÷ fuel economy.