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About The Carbon Footprint Calculator

Our carbon footprint comparator compares the annual CO2 output of cars powered by an internal combustion engine 'ICE' including petrol, diesel and hybrid engines.

Getting Started

To get started comparing the carbon footprint of different cars;

• Select a fuel type
• Choose a car
• Enter your annual mileage
• Click on the 'Calculate' button

You can repeat this process for each type of fuel you want so you can compare different cars side-by-side.

Electric Cars

For electric cars, when UK power stations create the electricity used for recharging they are mainly burning fossil fuels in the form of gas.

To allow for this in the calculation, we've included the CO2 created for each kilowatt of energy required to recharge an electric car for an hour.

Currently this is around 0.233kgs of CO2 produced for each kilowatt hour of electricity.

As the standard measure of CO2 output for petrol, diesel and hybrid cars is grammes of CO2 per kilometre driven, we've converted the power station CO2 to an equivalent CO2 GPK/m figure.

We've done this by dividing the battery capacity of the car (in kilowatt-hours) by its WLTP range to get the number of miles an electric car can travel on a kilowatt-hour of electricity.

Next we multiply the result by the CO2 created by generating the electricity to recharge the car for one mile of driving.

Finally we convert the figure from miles to kilometres so that the number displayed is equivalent to that used for cars (though we convert it back again to miles for the actual calculation of the tonnes of CO2 produced by your mileage each year).

Renewable Tarrifs

If you only ever recharge your electric car by a tariff which uses renewable energy as the sole source of electricity then you can adjust the CO2 GPK/m value to take account of this.

Just set the CO figure to '0' and we won't calculate the output for electric cars (you will need to do this each time you choose an electric car as we automatically reset the value when you choose a petrol/diesel/hybrid car).

Alternatively, if you use a renewable tariff part of the time you can adjust the CO2 figure according to the percentage of time recharged from renewables.

For example, if you recharge from renewables for 50% of the time then halve the CO2 figure displayed.

ICE Engines

For some petrol, diesel and hybrid cars the CO2 data is also available by the individual WLTP mileage cycles (urban, suburban, rural and motorway).

If we've got CO2 output figures for the individual cycles then we'll display these values too.

You can then optionally add your annual mileage in each individual CO2 cycle to make the carbon footprint calculation more accurate.

You can change your mileage as many times as you want and then see a recalculation of the results just by clicking on the 'Calculate' button.

Extended Data

For most petrol and diesel engined cars we will typically have the CO2 output of the vehicle in Grammes Per Kilometre as measured under the recorded Worldwide Harmonised Light Vehicles Test Procedure 'Combined' mileage cycle.

For these cars you can add your annual mileage in each cycle for the individual WLTP mileage cycles (urban, suburban, rural and motorway) and click he 'Calculate' button to see a calculation of the CO2 output for each cycle and the total too.

For hybrid cars the data changes slightly in terms of the point at which the CO2 output is measured - it is usually measured when battery charging is suspended in each cycle.

As you change the mileage in the individual cycles the total mileage will automatically adjust to calculate the total mileage entered for all of the cycles.

You can change your mileage for any of the cycles as many times as you want and then see a recalculation of the results just by clicking on the 'Calculate' button.