Is an inverter or conventional portable better for outages?

For just the essentials, an inverter generator is quieter and produces clean power safe for electronics, which is ideal for sensitive devices and overnight running. If you also need to start a well or sump pump, a conventional mid-large portable in the 5,000 to 7,500 watt range gives you the surge headroom at a lower cost per watt.

Best Generator for a Power Outage

Q: What size generator do I need for a power outage?

To keep the essentials running in an outage — refrigerator, gas furnace blower, lights, internet, and phone charging — you need about 1,500 running watts and a starting surge near 2,500 watts, which a 2,000 to 3,000 watt inverter or portable handles. If you have a well pump or sump pump, the startup surge pushes the requirement to a 5,000 to 7,500 watt portable.

Q: How big a generator to run a refrigerator and furnace?

A refrigerator runs near 200 watts but surges to about 1,200 watts at startup, and a gas furnace blower runs 600 to 700 watts with a surge to 1,000 to 1,600 watts. Together with lights and internet they total about 1,500 running watts and a roughly 2,500 watt peak, so a 2,000 to 3,000 watt generator runs them comfortably.

Short answer: to keep the essentials running in an outage — fridge, gas furnace blower, lights, internet, phone charging — you need about 1,500 running / 2,500 surge watts, which a 2,000–3,000W inverter or portable handles. Add a well or sump pump and the startup surge pushes you to a 5,000–7,500W portable. Central AC takes it to whole-house standby territory.

An outage generator’s job is to keep food cold, heat working, the basement dry, and the family connected — not to run the whole house. Sized to that real list, the right generator is smaller and cheaper than most people expect. The exception is a pump: a well or sump pump’s startup surge is what pushes you up a size class. Here’s the honest capacity and picks by class. Product links are Amazon affiliate links and never change the advice.

Outage sizing at a glance

What you back up	Approx running / surge watts	Recommended class
Bare essentials: fridge, lights, internet, charging	~700 / 1,700	2,000W inverter
Essentials + gas furnace blower + TV	~1,500 / 2,500	2,500–3,000W inverter/portable
Essentials + sump pump (wet-basement homes)	~2,550 / 3,650	4,000–5,000W portable
Essentials + well pump + sump pump	~3,350 / 5,350	5,000–7,500W portable

These follow the running-watts-plus-largest-surge method — a fridge (200/1,200), furnace blower (700/1,600), well pump (1,000/3,000), sump pump (1,050/2,150). Run your exact list →

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Outage generators by capacity class

Pick the class that matches your sizing result. Confirm the current rated and surge watts and, if you’ll feed a transfer switch, a 120/240V outlet before buying.

2,000–3,000W inverter — essentials, quiet, electronics-safe:

Honda EU2200i-class inverter ~2,200W, very quiet, clean power for electronics Check current price → Westinghouse iGen inverter Compact inverter for fridge, lights, internet Check current price → Champion inverter (~3,000W) Quiet inverter with headroom for a furnace blower Check current price →

5,000–7,500W portable — essentials plus a well or sump pump:

Champion dual-fuel portable Gas or propane, surge headroom for pump startup Check current price → Westinghouse WGen portable ~7,500W, 120/240V, transfer-switch ready Check current price → DuroMax dual-fuel portable High-surge portable for well-pump homes Check current price →

We earn commission on qualifying Amazon purchases at no cost to you. See our affiliate disclosure. Wattage ratings and prices change — verify the current rated/surge watts before buying.

The pump is what sizes up your outage generator

Without a pump, outage backup is a light job — the fridge, furnace blower, lights, and internet sit around 1,500 running watts, well inside a small inverter. The moment a well pump or sump pump enters the picture, the math changes, because pumps have the largest startup surge of any common home load. A 1/2 hp well pump runs near 1,000 watts but can spike to 3,000 watts or more at startup, and that surge — added on top of everything already running — is what forces you from a 3,000W inverter up to a 5,000–7,500W portable. If a sump pump is your one heavy load and your basement floods in storms, don’t skimp here: an undersized generator that can’t start the sump pump in a downpour defeats the purpose. See running vs starting watts.

Never run a generator indoors, in a garage, or near windows — carbon monoxide kills. And connect to your home only through a transfer switch or interlock installed by a licensed electrician per NEC and local code — never backfeed a generator into an outlet. Backfeeding can electrocute utility crews and start a fire when power returns.

Frequently asked questions

What size generator do I need for a power outage?

Essentials (fridge, furnace blower, lights, internet) need ~1,500 running / 2,500 surge watts — a 2,000–3,000W unit. With a well or sump pump the surge pushes you to a 5,000–7,500W portable. Central AC means whole-house standby. See whole-house.

How big a generator to run a refrigerator and furnace?

A fridge runs ~200W (surge ~1,200W) and a gas furnace blower 600–700W (surge 1,000–1,600W). With lights and internet that’s ~1,500 running / ~2,500 surge — a 2,000–3,000W generator.

Inverter or conventional portable for outages?

For just essentials, an inverter is quieter and clean for electronics. If you must start a well or sump pump, a mid-large 5,000–7,500W portable gives the surge headroom at lower cost per watt.

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