EV Charging Cost Calculator
Cost per mile at home, and against petrol
Work out what charging an electric car at home actually costs per mile and per year, compare it against the petrol car it replaced, and see what an off-peak tariff or your own solar does to the number.
The comparison
- Energy into the battery
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- Blended electricity price paid
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- Equivalent fuel economy
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- Fuel the old car would have burned
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- Saving over ten years
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Show the working
How this is calculated
Every assumption is listed so you can disagree with it. If a figure here is wrong, tell us and we will fix it.
The model
The figure that matters is what leaves your meter, not what reaches the battery. Charging is lossy, and those losses are billed to you:
battery kWh = distance × efficiency / 100 meter kWh = battery kWh / (1 − losses) blended $ = off-peak share × off-peak rate + solar share × 0 + remainder × peak rate
Ten percent is a reasonable default for AC charging losses at home: some goes to the on-board charger, some to battery thermal management, and some to the car simply staying awake while plugged in. Cold weather makes it worse, sometimes considerably.
Why solar is priced at zero, and why that is arguable
Charging from your own array is entered at zero cost, which is the simple view: the electricity was already yours. The stricter view is that it has an opportunity cost equal to whatever your utility would have paid you to export it. Where export rates are meaningful, set the solar share to zero and put your export rate in the off-peak field instead — that models it properly.
Off-peak charging is most of the benefit
An EV is the ideal off-peak load: it needs a lot of energy, and it does not care when it gets it as long as the car is full by morning. On a tariff with a genuine overnight rate this single setting often halves the running cost, and it is the reason a home charger on a timer beats public charging so decisively on price.
Set the off-peak share honestly. If you regularly top up during the day or rely on public rapid charging, the real number is well below 85%, and public rapid charging can cost more per mile than petrol.
What this leaves out
Running cost only. No purchase price difference, no depreciation, no insurance, no registration or road tax, no charger installation, and no maintenance — though the maintenance gap does favour the EV, with no oil changes, no exhaust and far less brake wear from regenerative braking.
It also assumes you have somewhere to charge at home. Without that, none of these numbers apply, and public charging economics are a different calculation entirely.
Sources
The constants and default values above come from these public sources. Every one is free to read and none of them are ours — check the figures against them.
- EPA / DOE — Fuel Economy for Electric Vehicles Official kWh per 100 miles ratings for specific models, to replace our efficiency default.
- DOE Alternative Fuels Data Center — Vehicle Cost Calculator A fuller total-cost-of-ownership model including purchase price and depreciation, which this tool excludes.
- EIA — Gasoline and Diesel Fuel Update Current pump prices for the petrol comparison.
- DOE — Charging at Home Charger levels, circuit requirements and why home charging is so much cheaper than public rapid charging.
Built by Vano Gelashvili
Vano Gelashvili is a software developer who builds the calculators on this site. He is not an HVAC engineer, and says so on every page: what he brings is the arithmetic, worked openly against published data.