EV Charging Cost Calculator

About the EV Charging Cost Calculator

Find out what charging an electric car costs — at home, at work or at a public charger. Enter the battery’s usable capacity, the charge you start and stop at, and the price per kWh (or per minute, with any session fee). The calculator works out the energy that goes into the battery, the extra energy drawn from the grid because charging is not 100% efficient, the cost of this charge and of a full one, and — with the charging power — how long it takes.

Add the car’s energy use to get the range added and the cost per km or mile, and compare it with a petrol, diesel or CNG car: the cost per km of each, the saving over a month and the distance it takes for that saving to pay back a higher purchase price. It works for electric cars, vans, scooters, motorbikes and e-bikes, in your own currency, and shows the working step by step. Without a pass, the free preview shows the cost of this charge in full, with the first step of the working; the other figures, the fuel-car comparison and Copy summary come with a Pro pass, or after unlocking this result.

Common uses

• Budgeting home charging on your electricity tariff, or checking a charging receipt.
• Comparing a public fast charger’s price per kWh or per minute with charging at home.
• Working out the cost per km of an electric car, scooter or motorbike.
• Deciding whether an electric car’s higher price pays off against petrol, diesel or CNG for the distance you drive.

How the cost is worked out

• Energy into the battery = usable capacity × (stop % − start %) ÷ 100.
• Energy from the grid = energy into the battery ÷ charging efficiency. Some energy is lost as heat while charging; the US government’s fueleconomy.gov guide to electric vehicles notes that battery charging efficiency “is often 84% to 93%”. At 90%, 27 kWh is drawn to store 24.3 kWh.
• Cost = energy from the grid × the price per kWh, or the charging minutes × the price per minute, plus any session fee.
• Charging time = energy from the grid ÷ the charging power — the lower of the charger’s power and the most the car accepts.
• Range added = energy into the battery ÷ energy use, and cost per km = cost ÷ range added.

The US Department of Energy works the same way: at 10.7 cents per kWh, a car using 27 kWh per 100 miles costs about 3 cents a mile, and filling an empty 54 kWh battery costs about $6 (Alternative Fuels Data Center: charging at home).

Which energy-use figure to enter

Electric cars show their energy use as kWh/100 km, Wh/km or km/kWh (kWh/100 mi or mi/kWh where distances are in miles). A figure from the car’s own display is usually the energy taken from the battery: choose measured by the car and the calculator adds the charging loss. A figure from a smart meter, a charger’s app or a charging receipt already includes the loss: choose measured at the charger or meter.

Use your own average over a few weeks where you can, and a winter figure for winter: fueleconomy.gov on cold weather reports that at 20 °F (about −7 °C), with the cabin heater on, an electric car’s range can drop by about 41% in mixed city and highway driving (about 12% with the heater off), that about two-thirds of the extra energy goes on heating the cabin, and that preheating the cabin while the car is plugged in extends its range.

Charging power and time

Charging at a socket or wall box (AC) is limited by the car’s on-board charger, and fast charging (DC) by the most the car accepts — enter that as the car’s maximum power. In the US, the Department of Energy lists a standard 120 V outlet (Level 1) at about 1.9 kW, most home Level 2 chargers at up to 7.2 kW (2.9 to 19.2 kW), and DC fast chargers at up to 500 kW, though many cars cannot charge faster than 200 kW (Alternative Fuels Data Center: charging stations).

Charging power varies with the car and the battery’s state of charge, so the time shown — at full power all the way — is the shortest the charge can take. fueleconomy.gov puts a full recharge at 3 to 12 hours, and a fast charge to 80% at about 30 minutes.

Prices per kWh and per minute

Home electricity and most public chargers are priced per kWh — an electricity bill often calls a kWh a unit — but some public chargers charge by the minute, add a session fee, or charge for the time a full car stays plugged in. With a price per minute, a car that charges slowly pays more for the same energy: the calculator turns the time at the power you enter into money. Some utilities offer time-of-use tariffs that make charging cheaper at certain hours: enter the price of the hours you charge in, taxes included.

Comparing with a petrol, diesel or CNG car

The fuel cost per km is the fuel price ÷ km per litre (or per kg of CNG), or the price × litres per 100 km ÷ 100; mpg is converted with 1 mile = 1.609344 km and a gallon of 3.785411784 litres (US) or 4.54609 litres (UK). The monthly saving is (fuel cost per km − electric cost per km) × the distance you drive a month, and the break-even distance is the extra purchase price ÷ that saving per km: how far you must drive before lower running costs have paid back a higher price.

The comparison covers energy and fuel only. Servicing, insurance, road tax, subsidies, resale value and battery wear can change the answer — the car ownership cost calculator adds them up.

Limitations

• The charging time assumes full power all the way; real sessions often take longer, because charging power varies with the car and the battery’s state of charge.
• Use the usable battery capacity from the car’s handbook or maker; an older battery holds somewhat less.
• Prices are not built in: enter your own tariff, with taxes, and the charger’s fees.
• The comparison counts energy and fuel only — not servicing, insurance, subsidies, resale value or battery replacement.

Privacy

On this device: nothing is sent

Everything is worked out in your browser and nothing you type is uploaded. Your units, currency and the last figures you used are remembered in this browser, so the next charge is quicker to cost.