EV Charging Cost Calculator

1. Pick Monthly driving to price a month of use, or One charging session to price a single charge.
2. For a month, enter your distance and the car's efficiency in kWh per 100 miles, miles per kWh, kWh per 100 km or km per kWh.
3. Say where the efficiency figure comes from. A window sticker or fueleconomy.gov rating is measured at the wall, so charging losses are already in it. A dashboard or trip computer figure is measured from the battery, so enter a charging efficiency to add the losses.
4. For one charge, enter the battery size, the start and end charge in percent, the charger power in kW and the charging efficiency.
5. Enter your electricity price. Turn on time-of-use if part of your charging is billed at an off-peak price.
6. Read the cost, the energy at the battery and from the grid, the cost per mile or the charging time, and the working below the result.

Divide the total of your power bill by the kWh used to get a price that includes delivery charges. The EIA Electric Power Monthly, Table 5.6.A lists average residential prices by state in cents per kWh.

Here d is the distance, e the efficiency in kWh per 100 of that distance unit and η (eta) the charging efficiency as a decimal, so 90% is 0.90. P is the price per kWh.

Only the dashboard figure is divided by the charging efficiency. The sticker rating is already measured at the wall.

Cost per year is the monthly cost x 12. Cost per 100 miles is the cost per mile x 100.

For example, 30 kWh per 100 miles is 100 / 30 = 3.33 miles per kWh. One mile is 1.609344 km.

f is the share of charging energy bought off-peak, as a decimal.

B is the usable battery size in kWh. The time is a best case, because charging slows as the battery gets close to full.

Each row is 1,000 miles a month at 30 kWh per 100 miles. As a window sticker rating that is 300.0 kWh from the wall. As a dashboard figure with 90% charging efficiency it is 333.3 kWh from the grid. The prices are examples only.

The cost rises in step with the price. Doubling the price per kWh doubles the cost per mile.

Not every kWh from the outlet ends up in the battery. Some is lost as heat in the charging cable and in the car's on-board charger. Whether you need to add these losses depends on where your efficiency figure was measured.

Window Sticker Ratings Already Include Them

The EPA says its MPGe values include charging losses. They assume Level 2 AC charging and count the losses in the cable and the on-board charger, which moves the measurement to the wall outlet. So a sticker or fueleconomy.gov kWh per 100 miles is used as it is. Dividing it by a charging efficiency would count the losses twice.

Dashboard Figures Need Them Added

A dashboard or trip computer reports energy drawn from the battery. To get the energy you pay for, divide by the charging efficiency: grid kWh = battery kWh / efficiency. At 90%, 1,000 miles at 30 kWh per 100 miles puts 300.0 kWh into the battery but draws 333.3 kWh from the grid. The extra 33.3 kWh costs $5.67 a month at $0.17 per kWh.

Level 1 vs Level 2: Check Your Charger

The loss is not a fixed number. It depends on the car, the charging equipment and the conditions. We use 90% as an editable example. If your charger or car app shows the kWh drawn from the wall and the kWh added to the battery, divide the second by the first to get your own figure.

The Alternative Fuels Data Center notes that some utilities offer residential time-of-use rates or other rate incentives for EV owners. On these plans the price per kWh depends on the hour, and it is often lower late at night.

Turn on time-of-use in the calculator and enter the share of charging you do off-peak and the off-peak price. The calculator blends the two prices by energy share. With 80% at $0.10 and 20% at $0.17, the average is $0.114 per kWh, and the 1,000-mile month at a sticker 30 kWh per 100 miles costs $34.20 instead of $51.00.

Plans differ in their hours, prices and fixed charges. Some also raise the peak price, which can make daytime charging cost more than before. Check the details with your utility before you switch.

The EPA says that if you can charge at home or at work with Level 1 or Level 2 equipment and have time to charge, it will usually be cheaper than DC fast charging.

How Stations Bill

FuelEconomy.gov notes that some public chargers are free. Others charge a flat fee per charge, a monthly subscription, by the electricity you use, or by how long you use the charger. To use this calculator with a per-minute or per-session price, divide what you paid by the kWh added and enter that as the price per kWh.

Speed Drops Near Full

The Alternative Fuels Data Center says charging times vary with how depleted the battery is, its capacity and the charging equipment. The EPA adds that DC fast charging beyond 80% tends to be significantly slower, so stopping near 80% generally saves time.

1. A driver covers 1,000 miles a month in a car whose window sticker says 30 kWh per 100 miles. Power costs $0.17 per kWh.
2. Energy from the wall: 1,000 x 30 / 100 = 300.0 kWh. No charging efficiency is applied, because the sticker already includes the losses.
3. Cost per month: 300.0 x 0.17 = $51.00. Cost per year: $612.00. Cost per mile: 5.10 cents.
4. If the 30 kWh per 100 miles came from the dashboard instead, the battery gets 300.0 kWh and the grid supplies 300.0 / 0.90 = 333.3 kWh.
5. That costs 333.33 x 0.17 = $56.67 a month, or 5.67 cents per mile. At $0.10 per kWh it would be $33.33.
6. One charge of a 75 kWh battery from 20% to 80%: 75 x 60 / 100 = 45.0 kWh added, 50.0 kWh from the grid, $8.50 at $0.17, and about 6 h 57 min on a 7.2 kW charger.

For a full cost comparison with a gas car, including fuel and upkeep, see our guide to electric vs gas car cost.

Multiply the miles you drive by the window sticker kWh per mile, then by your price per kWh. At 1,000 miles a month and 30 kWh per 100 miles, the car draws 300.0 kWh from the wall. That is $51.00 a month at $0.17 per kWh and $30.00 at $0.10 per kWh.

With a window sticker rating, cost per mile = kWh per 100 miles / 100 x price per kWh. For 30 kWh per 100 miles at $0.17 per kWh, that is 0.30 x 0.17 = $0.0510, or 5.10 cents per mile. If 30 kWh per 100 miles comes from the dashboard, divide by the charging efficiency too: at 90% it is 5.67 cents per mile.

Energy added = battery size x (end % - start %) / 100. A 75 kWh battery charged from 20% to 80% takes in 45.0 kWh. At 90% efficiency it draws 50.0 kWh from the grid, which costs $8.50 at $0.17 per kWh.

Yes. The EPA says its MPGe values include charging losses, measured from the wall outlet with Level 2 AC charging. So do not divide a sticker or fueleconomy.gov rating by a charging efficiency. A dashboard or trip computer figure is measured from the battery, so it does need it: 1,000 miles at 30 kWh per 100 miles is then 333.3 kWh from the grid at 90%, or $56.67 at $0.17.

Charging time is about grid kWh / charger power in kW. Drawing 50.0 kWh takes about 6 h 57 min at 7.2 kW and about 26.3 hours at 1.9 kW. Real sessions take longer near full, because charging slows as the battery fills. The EPA notes that DC fast charging beyond 80% tends to be much slower.

It can. Average price = off-peak share x off-peak price + the rest x the standard price. Charging 80% of the energy at $0.10 and 20% at $0.17 averages $0.114 per kWh, so the 1,000-mile month at 30 kWh per 100 miles drops from $51.00 to $34.20. Rate plans differ, so check the hours and prices with your utility.

Usually. The EPA says Level 1 and Level 2 charging at home or work will usually be cheaper than DC fast chargers. Public stations may charge by the kWh, by the minute, per session or through a subscription. For a per-minute price, divide the total you paid by the kWh added, then enter that price per kWh.

• U.S. EPA: Fuel Economy and EV Range Testing (MPGe values include charging losses; they assume Level 2 AC charging and count cable and on-board charger losses, measured at the wall outlet; a gallon of gasoline equals 33.7 kWh).
• U.S. EPA: Plug-in Electric Vehicle Charging: The Basics (DC fast charging beyond 80% tends to be significantly slower; Level 1 and Level 2 charging at home or work will usually be cheaper than DC fast chargers).
• Alternative Fuels Data Center: Developing Infrastructure to Charge Electric Vehicles (most residential Level 2 chargers run at up to 30 amps and 7.2 kW; Level 1 uses a 120 V plug; charging time varies with state of charge, capacity and equipment).
• FuelEconomy.gov: Charging Electric Vehicles (public chargers may be free or bill a flat fee per charge, a monthly subscription, by electricity used or by time connected).