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Tailpipe CO₂ calculator

Vehicles
Everyday

How much CO₂ does your car emit?

Grams of CO₂ per kilometre or mile, and kilograms a year, from what your petrol or diesel car burns.

Fuel

Tailpipe CO₂

153 g/km

2,289 kg of CO₂ a year over 15,000 km, from 975 L of fuel

CO₂ per distance and per year

CO₂ per distance and per year
PerCO₂
Kilometre153 g/km
Mile246 g/mi
Year (15,000 km)2,289 kg

Tailpipe CO₂ only: producing and delivering the fuel, other greenhouse gases and the car's manufacture are not included.

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Grams of CO₂ per kilometre or mile, and kilograms a year, from what your petrol or diesel car burns.

How to use

  1. Choose petrol or diesel.
  2. Enter your car's fuel consumption, in litres per 100 km, km per litre or miles per gallon.
  3. Enter how far you drive in a year to see the yearly total.

Tailpipe CO₂ at common fuel consumption levels

Consumption (L/100 km)Petrol (g/km)Diesel (g/km)
493.9107.6
5117.4134.5
6140.9161.4
7164.3188.2
8187.8215.1
10234.8268.9

How it works

Almost all the carbon in petrol and diesel leaves the exhaust as carbon dioxide, so the CO₂ a car emits follows from how much fuel it burns. The US Environmental Protection Agency (EPA) puts it at 8,887 grams of CO₂ per US gallon of petrol and 10,180 grams per gallon of diesel: about 2.35 kg per litre of petrol and 2.69 kg per litre of diesel. Diesel emits more per litre because it is denser and holds more carbon, but diesel cars usually burn fewer litres.

The formula is CO₂ (g/km) = consumption (L/100 km) ÷ 100 × grams per litre. A petrol car using 6.5 L/100 km emits 6.5 ÷ 100 × 2,347.7 ≈ 153 g/km; over 15,000 km a year that is about 2,290 kg. Miles per gallon are first turned into litres per 100 km (235.2 ÷ mpg for US gallons).

This is tailpipe CO₂ only. Producing, refining and delivering the fuel adds more, and so does building the car. Official type-approval figures (WLTP) come from a lab test and can differ from what you burn on the road; your own consumption gives your own number. E85, LPG and natural gas are not included because no official per-litre factor for them was available.

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Frequently asked questions

How much CO₂ does a litre of petrol make?

About 2.35 kg of CO₂ from the tailpipe, and a litre of diesel about 2.69 kg (US EPA factors).

How many g/km is 5 L/100 km?

About 117 g/km for petrol and 134 g/km for diesel.

Why is my result different from the car's official CO₂ figure?

The official figure comes from a standard lab test. Real driving, weather, load and speed change how much fuel you burn, so your own consumption gives a more realistic tailpipe figure.

Does doubling my annual distance double the emissions?

Yes, if fuel consumption stays the same. The yearly total is proportional to the distance driven.

Can I use this for an electric car?

No. This calculation uses petrol or diesel burned at the tailpipe. Electricity production and vehicle manufacture are outside its scope.

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