EV Charger Amperage Calculator
Wondering what size breaker for EV charger installation you need? Pick your charger's amperage and this free calculator tells you the required breaker size, the minimum copper wire gauge, charging power, and estimated miles of range per hour.
Enter your numbers
Your results
| Charging power | — |
| Estimated range per hour (est.) | — |
| Continuous-load minimum (amps × 1.25) | — |
How to use this calculator
Choose your EV charger's maximum amperage from the dropdown — this is usually printed on the charger itself or in its manual. Common home chargers are 32 A or 40 A; faster 48 A units are typically hardwired.
Leave the voltage at 240 V for a typical single-family home. If you live in a condo or building fed by three-phase power, switch it to 208 V so the charging power estimate is right.
Press Calculate (results update instantly as you change the inputs). Read off the required breaker size and the minimum copper wire gauge, then show these numbers to your electrician for a quote.
How it works
EV charging is a continuous load — it draws full current for three hours or more. The National Electrical Code (NEC) 125% rule says the circuit must be sized at 125% of a continuous load, so the math is: breaker size = charger amps × 1.25, rounded up to the next standard breaker size (15, 20, 30, 40, 50, 60 A — 70 A where the load exceeds 60 A).
The minimum copper wire gauge follows from the breaker size: 16 A → 12 AWG, 24 A → 10 AWG, 32 A and 40 A → 8 AWG, 48 A and 50 A → 6 AWG (copper THHN). This is a minimum guideline — long wire runs lose voltage, so your electrician may upsize the wire for distance, and local code can add requirements.
Charging power is volts × amps ÷ 1000 (kW). The miles-of-range-per-hour figure is an estimate using 3.5 miles per kWh; actual range depends on your EV's efficiency and driving conditions. Electrical work can be dangerous and usually needs a permit — always have a licensed electrician verify and install the circuit.
Frequently asked questions
Can I put a 48-amp EV charger on a 50-amp breaker?
No. EV charging is a continuous load, so the NEC 125% rule requires the breaker to be sized at 48 x 1.25 = 60 amps. A 48-amp charger needs a 60-amp breaker with 6 AWG copper wire. A 50-amp breaker would be undersized and could trip or overheat.
What wire size do I need for a 48-amp EV charger?
The minimum copper wire for a 48-amp EV charger is 6 AWG THHN. Long wire runs can cause voltage drop, so some electricians upsize to 4 AWG for runs over about 100 feet. Your local electrical code and a licensed electrician should confirm the final size.
Does an EV charger need a neutral wire?
Most 240-volt hardwired EV chargers need only two hot wires and a ground - no neutral. Many older dryer outlets are wired with two hots and a neutral but no ground, which is why they cannot simply be reused for EV charging without rewiring.
Can I charge my EV on a dryer outlet?
Sometimes, but only with the right setup and a licensed electrician's sign-off. Dryer outlets are typically 30-amp circuits, which safely support only up to a 24-amp EV charger under the 125% continuous-load rule. Many dryer outlets also lack a proper ground wire, and frequent plugging and unplugging wears them out - they are not rated for daily EV charging cycles.