40-Amp vs 48-Amp EV Charger: Which to Buy

A 40-amp charger delivers 9.6 kilowatts; a 48-amp charger delivers 11.5. That sounds like a clear win for 48 amps, but the decision is really about your panel and your car, not the spec sheet. A 40-amp unit usually installs on a circuit many homes can already spare and can be plug-in; a 48-amp unit demands a larger dedicated circuit and must be hardwired. And many cars cannot use 48 amps at all. This guide shows the arithmetic so you buy the one that actually helps you.

The circuit each one needs

EV charging is a continuous load, so the National Electrical Code requires the branch circuit to be sized at 125 percent of the charger's draw. That single rule sets the whole comparison. A 40-amp charger needs a 50-amp circuit (40 times 1.25 equals 50), which is typically wired with 6 AWG copper and can terminate in a NEMA 14-50 outlet - so a 40-amp charger can be plug-in and even portable. A 48-amp charger needs a 60-amp circuit (48 times 1.25 equals 60), also 6 AWG copper, and because no standard household receptacle is rated for a continuous 48-amp draw, a 48-amp charger must be hardwired.

The plug-in-versus-hardwired split is a real practical difference, not just a wiring detail. A plug-in 40-amp unit can be unplugged and taken with you, and it is easier to swap. A hardwired 48-amp unit is a permanent fixture. We cover the trade-offs in hardwired vs plug-in and the circuit sizing in 60-amp vs 50-amp circuit.

The catch most buyers miss: your car's onboard charger

A home charger only supplies AC; the car's onboard charger converts it and sets the real ceiling. Many EVs have an onboard AC charger that caps at 7.7 kilowatts (32 amps) or 9.6 kilowatts (40 amps). If your car tops out at 9.6 kilowatts, a 48-amp wall unit does absolutely nothing extra for it - the car simply pulls 40 amps and ignores the rest. You would pay for a 60-amp circuit and a hardwired install to charge at exactly the same speed a 40-amp unit gives you.

So the first thing to check is your vehicle's onboard AC charging rate. Only cars that accept the full 11.5 kilowatts / 48 amps can turn a 48-amp charger into faster charging. If yours caps lower, buy for the cap. We explain how to find that number in what amp EV charger do I need, and the broader 32-versus-48 case in 32-amp vs 48-amp charger.

The real-world difference is smaller than it looks

Even for a car that can use all 48 amps, the gap is modest. The step from 9.6 to 11.5 kilowatts is about 20 percent more power, which at three to four miles per kilowatt hour works out to only a few extra miles of range per hour - very roughly two to eight miles depending on efficiency. Overnight, that is the difference between a car that is full at 3 a.m. and one that is full at 1 a.m. For most drivers who plug in for eight or more hours, both finish long before morning, and the difference never matters.

When 48 amps is genuinely worth it

Buy the 48-amp unit when three things line up: your panel can spare a dedicated 60-amp circuit, your car's onboard charger actually accepts 11.5 kilowatts, and you can hardwire it. The classic case is a large battery paired with a fast onboard charger and a short daily charging window - a car you plug in late and need topped up early, or two big EVs sharing time. If any of those three is missing, a 40-amp charger is the smarter buy: cheaper to install, often plug-in, and no slower for your actual car.

For a 48-amp install, the Grizzl-E Ultimate is a dedicated, rugged hardwired unit built for the full 11.5 kilowatts, while the value-focused Emporia also reaches 48 amps when hardwired and adds energy monitoring. Compare the full lists in best 48-amp chargers and best 40-amp chargers.