40-Amp vs 48-Amp EV Charger

Shopping for a Level 2 charger, you’ll keep bumping into two numbers: 40 amps and 48 amps. They look close, and the marketing makes 48 sound like the obvious “more is better” pick. But those eight amps carry a chain of consequences — a bigger circuit, a hardwired-only install, and a real step up in cost — that don’t always pay off. Here’s the actual math on how much faster 48 amps is, what it costs you to get there, and which drivers genuinely benefit.

The two ratings, side by side

*Range estimates assume about 3.5 miles per kWh; real efficiency varies by vehicle, speed, temperature and terrain.

How much faster is 48 amps, really?

Start with the power. At 240 volts, a 40-amp charger delivers about 9.6 kW (40 × 240) and a 48-amp charger about 11.5 kW(48 × 240). To turn kilowatts into something intuitive, we assume a typical EV goes about 3.5 miles per kWh. That works out to roughly 34 miles of range per hour at 40 amps and about 40 miles per hour at 48 amps — a gap of around 6 miles per hour.

Six miles an hour sounds like something, until you place it against how people actually charge. Most drivers plug in overnight and add only 30 to 60 milesback — the distance they drove that day. A 40-amp charger replaces 60 miles in under two hours; you have all night. Unless your nightly top-up is huge or your charging window is unusually short, the extra 6 miles per hour simply finishes a job that was already going to be done by morning. The bigger speed story for most people isn’t 40 vs 48 — it’s Level 1 vs Level 2, where the jump is measured in multiples, not a few miles.

Why 48 amps costs more

The reason 48 amps is a genuine cost step comes straight from the code. EV charging is a continuous load, so NEC Article 625 requires the breaker to be rated at 125% of the charger’s current— equivalently, the charger may draw only 80% of the breaker’s rating. So a 40-amp charger needs a 50-amp circuit, and a 48-amp charger needs a 60-amp circuit (48 is 80% of 60).

That jump from 50 to 60 amps ripples through the whole install. It calls for heavier-gauge wire, a larger breaker, and more spare capacity in your panel— and if the panel is already near its limit, you could be looking at a load-management device or even a panel upgrade just to enable 48-amp charging. On top of that, a 48-amp unit must be hardwired: the largest common plug (NEMA 14-50) sits on a 50-amp circuit and caps a plug-in charger at 40 amps, so there’s no plug-in route to 48. A 40-amp charger, by contrast, runs on that common 50-amp circuit and can be plug-in, keeping the install simpler and often cheaper. We break that decision down in hardwired vs plug-in.

Who should get which

Match the charger to your driving, not to the bigger number:

• Get 40 amps if…you drive an average amount (say, under ~60 miles a day), charge overnight, want the option of a plug-in install, or your panel doesn’t have easy room for a 60-amp circuit. This covers the large majority of single-EV households.
• Get 48 amps if… you rack up high daily mileage, drive a large-battery vehicle or truck you frequently run low, share one charger between two EVs, or have a genuinely short charging window (for example, a narrow off-peak electricity rate) where every extra mile per hour helps — and your panel can carry the 60-amp circuit.

A practical middle path: many popular chargers are adjustableand can be set to 40 amps now and dialed up to 48 later. If you buy a 48-amp-capable unit but only install a 50-amp circuit today, you keep the door open — though reaching the full 48 amps down the road still means upgrading to a 60-amp hardwired circuit.

For most people, 40 amps is plenty: it refills far more than a typical day’s driving while you sleep, on a cheaper and more flexible install. Step up to 48 only when your mileage, battery size, or two-car garage actually needs it — and your panel can support it. Still deciding on the install itself? See hardwired vs plug-in, or return to the comparison hub for the rest of the choices.