Use this free calculator to convert EV charger amps to kilowatts (or kW to amps), find the breaker size a home charger needs, and estimate how many miles of range it adds per hour. It works for 240V homes, 208V apartment or commercial service, and 120V Level 1 charging.
EV Charger Calculator
Estimates only. Breaker size follows the 125% continuous-load rule for EV charging. Wire size, receptacle type and permits depend on your panel and local code. Confirm with a licensed electrician.
Calculator by HotGadgetsInfo
How the calculator works
- kW = amps × volts ÷ 1,000. A 32-amp charger on 240V delivers 7.68 kW. The same charger on 208V delivers about 6.66 kW.
- Breaker size = charging amps × 1.25, rounded up to the next standard breaker. EV charging counts as a continuous load, so a 32 A charger needs a 40 A circuit and a 48 A charger needs a 60 A circuit.
- Miles per hour of charging = kW × your car’s miles per kWh. Most EVs get 3 to 4 miles per kWh. Real results are a little lower because of charging losses and cold weather.
EV charger amps, kW and breaker size chart
| Charger amps | kW at 240V | kW at 208V | Breaker size | Approx. miles/hour (240V) |
|---|---|---|---|---|
| 12 A (Level 1, 120V) | 1.44 kW (120V) | — | 15 A / 20 A | about 5 |
| 16 A | 3.84 kW | 3.33 kW | 20 A | about 13 |
| 24 A | 5.76 kW | 4.99 kW | 30 A | about 20 |
| 32 A | 7.68 kW | 6.66 kW | 40 A | about 27 |
| 40 A | 9.60 kW | 8.32 kW | 50 A | about 34 |
| 48 A | 11.52 kW | 9.98 kW | 60 A | about 40 |
Related guides
- 7.7 kW to Amps: EV Charger Conversion Chart
- Can I Charge an EV on a 40-Amp Breaker?
- 40-Amp vs 48-Amp EV Charger
- NEMA 14-50 Outlet Requirements for EV Charging
- Plug-In vs Hardwired EV Charger
- Home EV Charger Installation Cost
- Best Level 2 EV Chargers for Home
Use this calculator on your site
Bloggers, installers and EV clubs are welcome to link to this calculator or use the chart above with credit and a link to hotgadgetsinfo.com/ev-charger-calculator.