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What size generator to run a Water heater (electric tank)?

Typical draw: 4500W running. 240V resistive load. On generator power, heat water in off-peak moments with other loads off — or skip it.

SIZING PLATE1 LOADS · +25% HEADROOM
Total running watts
4,500 W
Peak (largest start)
4,500 W
Buy at least
5,650 W rated
Look for ~5,650W running / 4,500W surge or better.

Right size: Mid-size portable (6,500W / 8,100W surge)

Typical price $700-1,200 · e.g. Westinghouse WGen6500, Champion 6250, Generac GP6500

Storm essentials with margin: fridge, freezer, sump pump, furnace fan, well pump (240V models), lights and electronics together. Louder open-frame design; electronics prefer models with THD under 5% or an inverter.

See current prices on Amazon

One size up: Large portable (9,500W / 12,500W surge)

Typical price $1,000-1,800 · e.g. Westinghouse WGen9500DF, DuroMax XP13000EH, Champion 12.5kW tri-fuel

Most of a house through an interlock kit: well pump, multiple large appliances, even a smaller central AC with a soft-starter. Heavy (200+ lbs), thirsty, and loud — this is serious-outage equipment, not camping gear.

See current prices on Amazon
Prefer battery over fuel? See what size power station runs a Water heater (electric tank).

Add more appliances

Real outages aren't one appliance. Adjust the full load below — your Water heater (electric tank) is pre-checked.

SIZING PLATE1 LOAD · +25% HEADROOM
Total running watts
4,500 W
Peak (largest start)
4,500 W
Buy at least
5,650 W rated
Look for ~5,650W running / 4,500W surge or better.

Peak assumes your largest motor starts while everything else runs — the honest worst case. Start big motors one at a time and a smaller unit may cope, but this number won't let you down.

Kitchen
Heating & cooling
Pumps & well
Electronics
Medical & safety
Lighting
Laundry
Household
Tools & outdoor
RV & camping

Generators that fit

Right size: Mid-size portable (6,500W / 8,100W surge)

Typical price $700-1,200 · e.g. Westinghouse WGen6500, Champion 6250, Generac GP6500

Storm essentials with margin: fridge, freezer, sump pump, furnace fan, well pump (240V models), lights and electronics together. Louder open-frame design; electronics prefer models with THD under 5% or an inverter.

See current prices on Amazon

One size up: Large portable (9,500W / 12,500W surge)

Typical price $1,000-1,800 · e.g. Westinghouse WGen9500DF, DuroMax XP13000EH, Champion 12.5kW tri-fuel

Most of a house through an interlock kit: well pump, multiple large appliances, even a smaller central AC with a soft-starter. Heavy (200+ lbs), thirsty, and loud — this is serious-outage equipment, not camping gear.

See current prices on Amazon
This site earns commissions from qualifying purchases made through links to Amazon and other retailers, at no extra cost to you. Wattage figures are typical estimates — actual draw varies by model. Always verify against your appliance's nameplate, and consult a licensed electrician for any panel or hardwired connections.