How we calculate cost-per-mile
With so many different charging networks and energy tariffs, it can be difficult to compare each one fairly. Especially when many of the public charging networks have different pricing structures to one another.
In order to compare each network and tariff fairly, we calculate an "indicative cost per mile". To calculate this, we apply the pricing of each network to a typical months usage with a "typical" EV.
- 616 miles - The average UK monthly mileage based on RAC Foundation data.
- 60 kWh - The size of battery used for our example EV.
- 80% - The amount we expect to charge the battery in each charge session.
- 3.5 miles per kWh - The efficiency used for our example EV.
With this information, we can see that we would need a total of 176 kWh to travel 616 miles. And with that number of 176 kWh we can easily enough work out how much each of the different tariffs would cost to charge.
We also take into account the number of charging sessions that may be needed (as they may well incur a per-charge fee).
And we also compare the cost-per-mile to that of petrol and diesel. For that comparison we use the Government's Advisory Fuel Rate prices for petrol and diesel, based on 1401 to 2000cc petrol engine sizes and 1601 to 2000cc diesel engine sizes.
Of course, this calculation is just indicative, it will vary based on driving style and the efficiency of individual vehicles. But, you can of course compare costs on a per-vehicle basis using our EV cost calculator, available for each vehicle in our database.
If you can think of ways we can improve our calculation, we'd love to know!