EV Charger Power and Range-per-Hour Calculator
Turn a charger's voltage and amperage into kilowatts, then estimate the miles of range added per hour of charging.
How it works
Power (kW) = volts × amps ÷ 1,000. Range added per hour = kW × 100 ÷ (kWh per 100 miles).
Worked example: 240 V × 30 A = 7.2 kW. At 30 kWh/100 mi, 7.2 × 100 ÷ 30 = 24 miles of range per hour.
Assumptions
- Nominal voltage and full rated current delivered continuously, with no losses beyond those already in the efficiency figure.
- The vehicle's onboard charger may limit the rate below the charger's rating.
- This tool does not size circuits or breakers. For installation questions, use a licensed electrician. The DOE notes a 30-amp (7.2 kW) Level 2 unit requires a dedicated 40-amp circuit.
Frequently asked questions
What power does a 240 V, 30 A charger deliver?
240 V × 30 A = 7,200 W = 7.2 kW, which matches the U.S. DOE Alternative Fuels Data Center's figure for most residential Level 2 chargers.
How many miles per hour does Level 2 add?
The DOE's Alternative Fuels Data Center lists approximately 25 miles of range per hour of Level 2 charging; the actual figure depends on charger power and vehicle efficiency.
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- EV charger amps to kW chart
- Watts, volts and amps calculator
Sources
Formulas and reference values are from these sources. Page last reviewed 2026-10-19.