How this calculator works
The energy the car uses is the miles driven times its efficiency in kWh per mile. Charging at home wastes a little as heat, so the energy drawn from your meter is higher: we divide by one minus the loss. Multiply the home energy by your price per kWh, and any public fast-charging energy by that price, and add them. The gas comparison divides the miles by mpg and multiplies by the price of a gallon.
Worked example: driving 12,000 miles a year at 30 kWh per 100 miles uses 3,600 kWh in the battery, or 4,000 kWh from the wall with 10% losses. At 17 cents that costs $680 a year ($57 a month), or 5.7 cents a mile. A 28 mpg gas car uses 429 gallons, which is $1,500 at $3.50. The saving is $820 a year. Adding 42 kWh to a 60 kWh battery (10% to 80%) on a 7.2 kW charger takes about 6.5 hours.
Yearly charging cost by electricity price (12,000 miles, 30 kWh per 100 miles, 10% losses)
Home charging only. Compare with the gas figure in the results.
| Price per kWh | Per year | Per month | Per mile |
|---|---|---|---|
| $0.10 | $400 | $33 | 3.3¢ |
| $0.13 | $520 | $43 | 4.3¢ |
| $0.17 | $680 | $57 | 5.7¢ |
| $0.22 | $880 | $73 | 7.3¢ |
| $0.30 | $1,200 | $100 | 10.0¢ |
| $0.40 | $1,600 | $133 | 13.3¢ |
Tips before you buy
- Charging at home overnight, on a time-of-use plan if you have one, is the cheapest way to charge. Public DC fast charging often costs two to three times as much per kWh.
- A Level 2 charger needs a 240 V circuit, usually a 40 or 50 amp breaker for a 32 to 40 amp charger. Have an electrician quote the circuit and check your panel has room.
- Efficiency falls in cold weather and at high speeds, by 20 to 30% or more in a hard winter. Preconditioning the car while it is plugged in helps.
- Charging to 80% rather than 100% is faster and easier on the battery for daily driving. Save a full charge for a long trip.
- Check for utility rebates, free or low-cost home charger programs and tax credits, which change often.
Tools & materials for this project
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Frequently asked questions
How much does it cost to charge an electric car at home?
About 5 to 6 cents a mile at 17 cents per kWh, or around $680 a year for 12,000 miles with an efficiency of 30 kWh per 100 miles. A gas car at 28 mpg and $3.50 would cost about $1,500.
How much does it cost to fully charge an EV?
A 60 kWh battery charged from empty needs about 67 kWh from the wall with 10% losses, which is about $11 at 17 cents per kWh.
How long does it take to charge an electric car?
About 6.5 hours to add 42 kWh (10% to 80% of 60 kWh) on a 7.2 kW Level 2 charger, and more than 30 hours on a standard 120 V outlet. A DC fast charger can do it in under an hour.
Is it cheaper to charge an EV at home or at a public charger?
Home is almost always cheaper: public DC fast charging typically costs two to three times as much per kWh as residential electricity.
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