How we work out our numbers
The formula behind every cost and charging time we calculate ourselves, and the inputs we use today.
Last updated: 16 October 2026
What we calculate, and what we don't
Most figures on EV Compared come straight from a named source: list prices and WLTP range from manufacturers, tax rules from GOV.UK, charging prices from the networks. Where a page shows a figure we worked out ourselves, such as a cost per mile, the cost of a charge or a charging time, it links here. This page sets out the sums and the inputs so you can check them, or redo them for your own car and tariff.
Cost per mile
Cost per mile is the price of a kWh divided by the miles the car covers on one kWh. At 6.66p per kWh, EDF GoElectric's off-peak rate, a car that covers 3.5 miles per kWh costs 1.9p a mile. At the 79p rapid charging average the same car costs 22.6p a mile.
Miles per kWh comes from the model's official WLTP consumption figure, unless the page names an independent real-world test instead.
Cost of a charge
The cost of a charge is the energy added times the price per kWh. Adding 60kWh costs £15.79 at the 26.32p price cap rate and £4.00 on EDF GoElectric.
Charging times
We quote the manufacturer's published charging times where they exist. For rapid charging that is the 10 to 80% time, because DC charging slows as the battery fills. Where we work out a home charging time, we divide the energy added by the lower of the charger's power and the car's onboard charger. That ignores the small losses as energy goes into the battery, so real times run a little longer, and the page says so.
The inputs we use today
| Input | Rate | Source | Checked |
|---|---|---|---|
| Intelligent Octopus Go off-peak (11:30pm to 5:30am) | 7.6p per kWh | octopus.energy | 16 October 2026 |
| EDF GoElectric off-peak (11pm to 6am) | 6.66p per kWh | edfenergy.com | 16 October 2026 |
| British Gas EV Power off-peak (midnight to 5am) | 9.5p per kWh | bestchargers.co.uk | 16 October 2026 |
| Ofgem price cap, 1 October 2026 to 31 December 2026 | 26.32p per kWh | energymadeeasy.co.uk | 16 October 2026 |
| Public rapid and ultra-rapid average, September 2026 | 79p per kWh | Zapmap Price Index | 16 October 2026 |
| Public slower chargers average, September 2026 | 54p per kWh | Zapmap Price Index | 16 October 2026 |
When we update
We re-check these inputs at least once a month, and whenever a supplier, Ofgem or a charging network changes a price. Pages that use them show the date their figures were checked. The editorial policy covers how we source everything else, and how to report a mistake.