How the calculator works
Charge time is the energy you add divided by the power your car actually accepts. The calculator multiplies your battery size by the percentage you want to add, then divides by the lower of your charger's output and your car's onboard charger, with about 90 percent efficiency for losses.
Vehicle figures come from our vehicle charging guides, which use automaker documents. Where an automaker publishes a system or rated battery figure rather than usable capacity, the calculator says so, and real times will be a little shorter. If your car is not listed, choose "My car is not listed" and enter the battery and onboard charger figures from your owner's manual.
Which setup do you need?
Pick the setup that refills your typical day's driving overnight with time to spare. For most commutes, a 32 to 48 amp Level 2 circuit does that easily. Going bigger than your car's onboard charger adds cost without adding speed, which the comparison table makes visible.
See what size breaker an EV charger needs, 40 amp vs 48 amp and Level 1 vs Level 2. Then use the charger finder for chargers that fit your car.
Charging time questions
How is the charge time calculated?
Energy needed is your battery size times the percentage you want to add. That energy is divided by the charging power, which is the lower of your charger's output and your car's onboard charger, and adjusted for about 90 percent charging efficiency.
Why does a bigger charger not always charge faster?
Your car's onboard charger caps how much Level 2 power it can accept. If the car takes 7.7 kW, a 48 amp, 11.5 kW charger charges it at 7.7 kW, the same as a 32 amp charger. The calculator shows when your car is the limit.
Why might real charging take longer than the estimate?
Cold batteries, preheating the cabin while plugged in, and the car slowing the last few percent near full all add time. In Ogden and Eden winters, plan for longer sessions than the estimate, especially in an unheated garage or driveway.
Know what you need? Send your car model and a photo of your panel.
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