Will a 7500 watt generator run a house?

It runs the essentials of most houses comfortably — refrigerator, freezer, furnace blower, sump pump, well pump, lights and outlets — but usually not central air conditioning or an electric range at the same time. Electric heat and electric water heating are generally out of reach.

What size generator do I need to run central air?

It depends on the unit's starting surge more than its running draw. Many central AC systems need a generator in the 10 kW to 14 kW range to start reliably, though a soft-start device can substantially reduce that requirement and is often cheaper than a bigger generator.

Can a generator run an electric water heater or range?

Only a large one. A typical electric water heater is around 4,500 W and an electric range can exceed 8,000 W — both are big enough that they usually only feature on whole-house standby systems, and even then load management may cycle them.

What Can a Generator Run? By Wattage

Updated 2026-08-16 · 7 min read

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Generator wattage tables are often written as if nothing surges. Motors do, and that's what determines whether a generator actually runs a load rather than tripping when it starts.

These figures account for that. See starting watts vs running watts for the mechanism.

How many watts do household appliances use?

Appliance	Running W	Starting W
LED lighting (whole house)	100–200	same
Phone/laptop charging	50–150	same
Refrigerator	150–250	800–1,200
Chest freezer	100–200	600–1,000
Furnace blower (gas furnace)	400–800	1,200–2,400
Sump pump	600–1,000	1,800–3,000
Well pump (1/2–1 HP)	800–1,500	2,400–5,000
Microwave	1,000–1,500	same
Coffee maker	800–1,200	same
Space heater	1,500	same
Window AC (10,000 BTU)	1,000–1,200	3,000–3,600
Central AC (3 ton)	3,000–3,500	10,000–15,000
Electric water heater	4,500	same
Electric range (one element)	2,000–3,000	same
Electric dryer	5,000	same
Well-equipped home office	300–600	same

Nameplates vary widely. Use these to plan and the nameplate to decide.

What can each size of generator run?

2,000 W inverter

Realistically: a refrigerator or modest lights and device charging. Not both plus anything else.

Won't do: well pump, sump pump, most furnace blowers, any air conditioning.

Best suited to camping, tailgating, and keeping phones and a fridge alive in a short outage. Quiet and portable, which is much of the point. See RV and camping generators.

3,500–4,000 W

Realistically: refrigerator, lights, device charging, and one motor load such as a sump pump or a furnace blower — but not both large motors at once.

Marginal: well pump, depending on size and whether anything else is running.

This is the practical minimum for meaningful outage coverage in a home with a well or a sump.

5,000–6,500 W

Realistically: refrigerator, freezer, furnace blower, sump pump, lights, and a microwave — with staggered use of the largest items.

Possible: a well pump, with headroom managed.

Won't do: central air conditioning, electric water heating, electric range.

A common and sensible portable size for storm outages in a gas- or oil-heated home.

7,500–9,500 W

Realistically: all the essentials of most homes simultaneously — refrigerator, freezer, furnace, sump, well pump, lights, outlets, and a window AC.

Marginal: central air conditioning, depending on the unit's surge and whether a soft starter is fitted.

Won't do: electric heat, or an electric range and water heater together.

This is the sweet spot for a large portable or a small standby unit, and it covers most households' realistic needs.

10,000–14,000 W

Realistically: essentials plus central air conditioning, with a soft starter making it comfortable rather than marginal.

Possible: an electric water heater, if managed against other loads.

Typically standby territory. This is where "the house feels normal during an outage" starts.

18,000–22,000 W and up

Realistically: whole-house operation including central air, electric water heating, and an electric range, usually with automatic load management shedding lower-priority circuits during peaks.

Standby only, with a natural gas or large propane supply. Required for all-electric homes, or homes with heat pumps and electric backup heat — which is a very large load, see heat pump backup heat explained.

Which appliances use the most generator power?

Four things determine which bracket you land in:

Central air conditioning. Its starting surge is usually the single largest demand in a house. A soft starter reduces it substantially and often costs far less than moving up a generator size — price both.

Well pump. Surges hard, and it's non-negotiable if you have no municipal water. Size for it explicitly.

Electric heat. Resistance heating is enormous — a 15 kW strip heater is 15,000 W on its own. Homes with heat pumps and electric backup generally need a large standby unit or the acceptance that heat runs on the heat pump only.

Electric water heating and cooking. Both large, both usually deferrable during an outage. Many households simply do without them and size smaller.

How do you calculate what your generator can run?

List what you actually need during an outage — not everything you own
Add running watts for anything running simultaneously
Add the largest single starting surge, not all of them
Add ~20% headroom for real-world conditions and future loads
Check against the generator's running rating, not its surge rating

Do it with the generator sizing calculator, then estimate fuel burn with the generator runtime calculator.

Where to go next

More in our generator and backup power guides.

Frequently asked questions

A refrigerator or a few lights and device charging, but not simultaneously with much else — and typically not a well pump or a furnace with a large blower, because the starting surge exceeds what a 2,000 W unit can supply.

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