How the comparison works

A petrol car emits CO₂ when it burns fuel: about 2.31 kg for every litre. An electric car has no exhaust, but the electricity it uses was generated somewhere, and that generation has a footprint.

The calculator multiplies the distance you drive by each car’s consumption. For petrol it applies 2.31 kg of CO₂ per litre. For the electric car it applies the carbon intensity of electricity in the country you select, taken from our electricity mix data.

Why the country matters

The same electric car can be almost emission-free in one country and only slightly better than petrol in another. This table uses a car that needs 18 kWh per 100 km and compares it with a petrol car using 7 litres per 100 km, which emits about 162 g of CO₂ per kilometre.

As a country adds wind, solar or other low-carbon power, every electric car already on its roads gets cleaner. A petrol car emits the same per litre for its whole life.

What the calculator leaves out

It covers driving only. It does not include building the car and battery, producing and transporting the petrol, or losses when charging. Manufacturing adds more to the electric car and fuel production adds more to the petrol car, so the two partly offset each other. For a full life-cycle comparison, use this result as the driving part of the picture.

The electricity figures are estimates of the national average. If you charge mostly from your own solar panels, or at times when the grid is cleaner, your real figure will be lower.

Frequently asked questions

Is an electric car always cleaner than a petrol car?

Not always, but nearly. It depends on how the electricity is generated. With the default figures in this calculator, an electric car emits less CO₂ per kilometre than a petrol car in 203 of the 209 countries and territories in our data. The exceptions are places where almost all power comes from coal or oil.

Does the calculator include making the car and battery?

No. It compares emissions from driving only: burning petrol in one case and generating the electricity in the other. Building an electric car, and especially its battery, causes more emissions than building a petrol car, and that difference is paid back over the first years of driving.

Which consumption figures should I use?

Use the real-world figures for the cars you are comparing. A typical petrol car uses 6 to 8 litres per 100 km and a typical electric car 15 to 20 kWh per 100 km. Larger and faster vehicles use more.

How do I convert miles per gallon?

Divide 235.2 by the US mpg figure, or 282.5 by the UK mpg figure, to get litres per 100 km. One mile is 1.609 km.