How many watts does an electric water heater use?
Updated
Running watts
4,000 W
Starting watts
4,000 W
Energy per day
8.0 kWh
An electric water heater typically draws about 4,000 watts while running. At about 2 h of use a day, that is roughly 8.0 kWh per day. These are typical values from generator wattage charts: the label on your own appliance (or its EnergyGuide sticker) gives the exact figure.
What size generator do I need for an electric water heater?
Plan for at least 4,800 W: 4,000 W to get through the start-up surge, plus a 20% margin so the generator never runs flat out. Of the common sizes, a 5,000 W generator is the smallest that fits.
| Generator | Can it run an electric water heater? |
|---|---|
| 2,000 W | No |
| 3,500 W | No |
| 5,000 W | Yes |
| 7,500 W | Yes |
| 10,000 W | Yes |
| 15,000 W | Yes |
How long will a power station run an electric water heater?
Running continuously at 4,000 W, assuming 85% of the battery is usable. The station's AC output must also handle the 4,000 W start-up surge.
| Battery capacity | Runtime |
|---|---|
| 1,000 Wh | about 13 min |
| 2,000 Wh | about 26 min |
| 3,600 Wh | about 46 min |
Running more than one appliance?
Starting surges don't add up the way running watts do. Pick everything you want to power to get your real number.
Open the Generator Size Calculator for Your HomeFrequently asked questions
What size generator do I need to run an electric water heater?
At least 4,800 W: 4,000 W to cover the start-up surge, plus a 20% safety margin.
Can a 2,000 watt generator run an electric water heater?
No. It needs about 4,000 W for a second or two when it starts, more than 2,000 W.
Can a 3,500 watt generator run an electric water heater?
No. It needs about 4,000 W for a second or two when it starts, more than 3,500 W.
How long will a 1,000 Wh power station run an electric water heater?
About 13 min, assuming 85% usable capacity, as long as the station's AC output is rated for 4,000 W of surge.
Never run a generator indoors or in a garage: see the CPSC safety guide.