EV Charging Calculator
This EV charging calculator works out how long an electric car takes to charge and what the charge costs. Enter the battery size, the starting and target charge, the charger power, and your electricity price, and the EV charging calculator returns the charging time, the energy added, the energy drawn from the grid, the cost, and the range you gain.
Results
The EV Charging Calculator is part of our Cost & Usage collection. Browse more cost & usage to size, convert, and check your work alongside this tool.
What the EV charging calculator does
Charging time depends on how much energy the battery needs and how fast the charger supplies it. Some energy is lost as heat in the charger and battery, so the grid supplies more than the battery stores. The EV charging calculator finds the energy to add between your start and target charge, allows for charging losses, and divides by the charger power for the time and by your price for the cost.
EV charging time formula
Range added is energy added × miles per kWh. AC charging runs near 85 to 92% efficiency. DC fast chargers taper the power above about 80%, so the formula gives a best case for them.
EV charging calculator example
A 75 kWh battery from 20% to 80% on a 7.2 kW Level 2 charger, 90% efficiency, at 0.16 per kWh:
At 3.5 miles per kWh that adds about 158 miles, a cost of about 0.051 per mile.
How to use the EV charging time calculator
Enter the usable battery capacity of your car in kWh, the current charge, and the charge you want; many drivers stop at 80% for daily use. Enter the charger power: about 1.4 kW for a standard outlet, 7 to 11.5 kW for Level 2, and 50 kW or more for DC fast charging. Add your electricity price and the car's efficiency in miles per kWh for cost and range. Press Calculate.
Reading your electric car charging cost
Home charging on Level 2 refills a typical daily drive in an hour or two overnight. Cost per mile is the fairest way to compare with gasoline: at 0.051 per mile, the example costs about a third of a car using 30 miles per gallon at 4.50 a gallon. Public fast chargers often charge more per kWh, which can double the cost per mile.
When to use an EV charging cost calculator
- Choosing between a Level 1 and Level 2 home charger
- Planning a road trip with fast charging stops
- Estimating the monthly cost of charging at home
- Comparing the running cost with a gasoline car
- Checking whether a time-of-use rate saves money
Common EV charging calculator mistakes
- Using total battery size. Use the usable capacity.
- Ignoring charging losses. The grid supplies about 10% more.
- Assuming fast chargers hold full power. They taper near full.
- Using the car's maximum AC rate. The charger may be slower.
Tips for electric car charging time
- Charge to 80% for daily driving to protect the battery.
- Schedule charging for off-peak hours.
- Precondition the battery before fast charging in cold weather.
Home EV charging cost and your electrical panel
A 48 A Level 2 charger draws 11.5 kW, as much as an electric range at full power. Before installing one, add it to the electrical load calculator to see whether the service has room. A 32 A charger at 7.7 kW covers most daily driving overnight and fits more existing panels. Time-of-use rates that drop the price at night can cut the charging bill by half.
EV cost per mile vs other running costs
Charging is only one running cost, but often the largest after depreciation. Use the energy cost calculator to compare it with other loads in your home. For smaller vehicles and equipment with lead-acid or lithium packs rated in amp hours, such as golf carts and e-bikes, the battery charge time calculator works in Ah and amps instead of kWh.
Level 2 charging time and other speeds: 75 kWh battery, 20% to 80%
| Charger | Power | Time (best case) |
|---|---|---|
| Level 1, 120 V 12 A | 1.4 kW | 35 h 43 min |
| Level 2, 240 V 30 A | 7.2 kW | 6 h 57 min |
| Level 2, 240 V 48 A | 11.5 kW | 4 h 21 min |
| DC fast, 50 kW | 50 kW | 1 h 0 min |
| DC fast, 150 kW | 150 kW | 0 h 20 min |
EV Charging Calculator FAQ
How long does it take to charge an electric car?
From 20% to 80% on a 75 kWh battery: about 6 h 57 min on a 7.2 kW Level 2 charger, and under half an hour on a 150 kW fast charger in ideal conditions.
How much does it cost to charge an electric car?
Grid kWh × price. Adding 45 kWh to the battery draws about 50 kWh, which costs 8.00 at 0.16 per kWh.
How do I convert kWh to miles?
Multiply by the car's efficiency. At 3.5 miles per kWh, 45 kWh gives about 158 miles.
Why does fast charging slow down near full?
Batteries accept less power as they fill to protect the cells, so the last 20% takes much longer.