How Many Watts to Run a House on a Generator?

The reason "how many watts to run a house" gets answered badly is that it conflates three very different ambitions. Deciding which one you are actually buying is most of the work.

Survival: 970 running watts

Food stays safe, you can see, and you can reach people. After derating that is about 1,250 running watts — and the surge requirement of 3,170 watts is the binding constraint, not the running load.

This set is a battery power station job, not a generator job. A 2 kWh unit with a 3,000 watt surge rating covers it for a day and a half, indoors, silently, with no fuel. If you are at this level and still shopping for generators, you are about to spend more money for a worse experience.

Essential: 3,500 running watts

Add the loads whose failure costs real money — heat, water, and keeping the basement dry.

About 4,400 running watts after derating. This is the set most people mean when they say "run my house", it needs a generator rather than a battery because of the pump surges, and a 5,000-6,500 running-watt dual fuel machine through a 30 amp transfer switch is the standard answer.

Comfortable: 8,000 running watts

Now you are adding things you want rather than things you need: kitchen outlets so the microwave and coffee maker work, a laundry circuit, and one window air conditioner.

That is 11,500 running watts after derating, which is a tri-fuel machine and a 50 amp connection. And the honest observation is that you can get most of the comfort for a fraction of that by simply not running the microwave and the coffee maker at the same time as everything else — appliances used for a few minutes do not need to be in a simultaneous-load calculation at all.

The short answer

The machine for each circuit set

#	Product	Best for	Score	Price
1	WEN DF8000X 8,000W Dual Fuel The best-value correctly-sized home backup generator here: enough for every essential circuit, dual fuel, CO shutoff, a real transfer-switch outlet, and no money spent on capacity you will not use.	Essential circuits, dual fuel, lowest cost	8.5/10★★★★★	$623.17
2	Westinghouse WGen9500DF 12,500W Dual Fuel The most broadly sensible home backup generator on the market: enough running watts for a whole essential-circuit panel, both transfer-switch outlets, and dual fuel — with the caveat that it has no CO shutoff.	The default whole-house pick	8.8/10★★★★★	$999.00
3	Westinghouse WGen11500TFc 14,500W Tri-Fuel Buy this when the sizing math genuinely lands above 10,000 running watts — not because bigger feels safer.	Larger homes with real 240V loads	8.9/10★★★★★	$1,499.00

#ad Prices as of October 5, 2026; they may have changed since. Scores are our editorial judgment from published specifications, not test results — how we pick. How we are funded.

Work your own version with the load calculator, which does this arithmetic on your actual appliance list and tells you which wattage class you land in.