40 A vs 48 A home EV chargers: is the upgrade worth it?
Updated · Reviewed against the current ChargerAtlas dataset
Short answer: 48 A is 20% faster (11.5 kW vs 9.6 kW) but must be hardwired to a 60 A circuit. If your car's onboard charger accepts 11 kW+ and your panel has the headroom, take the 48 A unit; if you want a plug-in install on a NEMA 14-50 outlet, 40 A is the ceiling — and for most overnight charging it's genuinely enough.
The electrical difference
At 240 V, power is simply amps × 240 ÷ 1000: a 40 A charger delivers 9.6 kW and a 48 A charger 11.5 kW. Because the National Electrical Code treats EV charging as a continuous load, the circuit must be rated at 125% of the charging current:
| Charger | Power at 240 V | Circuit required | Installation |
|---|---|---|---|
| 40 A | 9.6 kW | 50 A breaker | Plug-in (NEMA 14-50) or hardwired |
| 48 A | 11.5 kW | 60 A breaker | Hardwired only |
That last column is the decision most buyers miss: since receptacle circuits top out at 50 A in practice, 48 A charging always means hardwiring. If a plug-in installation matters to you (renting, planning to move, easy replacement), the comparison is over — choose from the 68 certified 40 A chargers.
What 20% faster means in hours
Real speed is capped by whichever is lower: the wall unit or the car's onboard AC charger. Empty-to-full times computed from our dataset (battery ÷ real rate, no taper):
| Vehicle | Rate at 40 A | Rate at 48 A | 0–100% at 40 A | 0–100% at 48 A | Time saved |
|---|---|---|---|---|---|
| Tesla Model Y | 9.6 kW | 11.5 kW | 7.8 h | 6.5 h | 1.3 h |
| Hyundai Ioniq 5 | 9.6 kW | 10.9 kW | 8.8 h | 7.7 h | 1.0 h |
| Ford Mustang Mach-E | 9.6 kW | 10.5 kW | 9.5 h | 8.7 h | 0.8 h |
| Chevrolet Equinox EV | 9.6 kW | 11.5 kW | 8.9 h | 7.4 h | 1.5 h |
| Kia EV9 | 9.6 kW | 10.9 kW | 10.4 h | 9.2 h | 1.2 h |
| Rivian R1S | 9.6 kW | 11.5 kW | 14.1 h | 11.7 h | 2.3 h |
Full-battery times overstate daily reality: a 40-mile day needs only ~10–13 kWh, about 75 minutes at 9.6 kW. Both sizes finish a typical day's driving long before morning.
When 48 A is worth it
- Big battery, deep discharges. On a 99.8 kWh Kia EV9 or a 135 kWh Rivian, the ~1.5–2 hours saved per full charge is the difference between "done overnight" and "not quite".
- You're hardwiring anyway. Outdoor installs favor hardwiring regardless (see the outdoor guide), and the wire-cost difference between a 50 A and 60 A circuit is small on short runs.
- Short charging windows. If you charge only during a cheap time-of-use window (say, midnight–6 a.m.), 20% more power means 20% more range banked per window.
When 40 A is the smarter buy
- Your car can't use 48 A. 4 of the 29 EVs in our database — including the Nissan Leaf, Ariya, Toyota bZ4X, and Subaru Solterra — accept 9.6 kW or less, so a 48 A unit adds exactly nothing. Check yours in the onboard-limit guide.
- Panel headroom is tight. A 50 A circuit is easier to fit into a loaded 100 A panel than a 60 A one; sometimes it's the difference that avoids a service upgrade (see circuit sizing).
- You value the plug. A NEMA 14-50 install moves with you and makes swapping a failed unit a five-minute job.
Both segments are deep: our database lists 68 40 A and 130 48 A certified chargers. Once you've picked the amperage, the best-charger-by-EV pages rank them for your specific car.