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EV Charging Cost Calculator

See what charging an electric car really costs: for a single charge, per mile or kilometre, and per month, compared with running a petrol car.

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How to use the EV Charging Cost Calculator

  1. 1Choose One charge or Cost per distance.
  2. 2For one charge, enter the battery size, the start and end charge levels and your electricity price.
  3. 3For running costs, enter your car's consumption, the distance you drive and how much charging is done in public.
  4. 4Add a petrol car's fuel economy and fuel price to compare.

How it works

The energy a charge adds is the battery capacity multiplied by the change in charge level: taking a 60 kWh battery from 20% to 80% adds 36 kWh. Charging is not perfectly efficient — some energy is lost as heat in the charger and battery — so more is drawn from the grid than ends up in the battery. Home charging typically loses around 10%, which is the default efficiency here.

Running cost per mile or kilometre comes from the car's consumption — shown on its dashboard or in its specification as kWh per 100 km, kWh per 100 miles or miles per kWh. Divided by charging efficiency and multiplied by your electricity price, it gives the cost of each mile or kilometre. Public rapid chargers usually cost several times more per kWh than home electricity, so the share of public charging matters.

The petrol comparison converts fuel economy into fuel used per mile or kilometre and multiplies by the fuel price, using exact gallon sizes: a US gallon is 3.785 litres and a UK gallon 4.546 litres, which is why UK mpg figures look higher for the same car.

The formula

cost per charge = battery × (end % − start %) ÷ efficiency × price per kWh
battery
usable battery capacity in kWh
efficiency
the share of grid electricity that reaches the battery

Running cost per distance = consumption ÷ efficiency × electricity price.

Worked example

Charging a 60 kWh battery from 20% to 80% at $0.15 per kWh

  1. Energy added: 60 kWh × (80% − 20%) = 36 kWh.
  2. Drawn from the grid at 90% efficiency: 36 ÷ 0.9 = 40 kWh.
  3. 40 kWh × $0.15.

Result: $6.00 for the charge.

Frequently asked questions

How much does it cost to fully charge an electric car?
Divide the battery size by the charging efficiency and multiply by your electricity price. A 60 kWh battery at $0.15 per kWh costs about $10.00 from empty to full at home.
Is it cheaper to charge at home?
Almost always. Home electricity — especially on an off-peak tariff — usually costs far less per kWh than public rapid charging.
Why does my car use more energy in winter?
Cold batteries are less efficient and heating the cabin draws power, so consumption rises in cold weather. Use a winter figure from your car's trip computer for a realistic estimate.
Should I charge to 100%?
Many manufacturers recommend charging to around 80% for everyday use and to 100% before long trips. Check your car's handbook, as advice differs between battery types.

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