What will a 4,000 watt generator run?

A 4,000 watt generator sits between the small camping units and the big home-backup ones. Many are inverter generators: quiet enough for a campground, strong enough for one RV AC. Here's what fits.

First, which 4,000 is it?

Generators have two ratings:

• Starting (peak) watts: a short burst for starting motors.
• Running (rated) watts: what it can give all day.

On many 4,000 W inverters, "4,000" is the peak. Westinghouse's iGen4000DFc, for example, is 4,000 peak and 3,300 running on gas. WEN's DF480iX is a bit bigger: 4,800 peak and 4,000 running.

Below, we assume 3,300 running and 4,000 starting watts. If yours is rated higher, you have more room.

Will a 4,000 watt generator run an RV air conditioner?

AC	Running W	Starting W	On 3,300 run / 4,000 start
13,500 BTU roof AC	1,500–2,000	2,800–3,500	Yes, plus a fridge, lights and TV
15,000 BTU roof AC	2,000–2,500	3,500–4,500	Borderline. Fine with a soft start, or on a 4,800 W peak unit
Two 13,500 BTU ACs	3,000	4,500	No, not both at once
Window AC, 8,000–10,000 BTU	750–1,200	2,000–2,400	Yes, plus the fridge

AC ranges are from Champion's chart. A soft start kit cuts an AC's start-up surge; Micro-Air sells one for RV ACs. The tool above is set up for a 13,500 BTU AC and the basics.

A worked example: a camper with one AC

• Running: 1,500 (AC) + 400 (fridge) + 100 (lights) + 150 (TV) + 80 (chargers) = 2,230 W
• Biggest surge: the AC, 3,000 − 1,500 = 1,500 W
• Starting: 2,230 + 1,500 = 3,730 W
• With 20% headroom: about 2,700 running and 4,500 starting watts

It fits a 3,300 / 4,000 generator, but the start is close. Start the AC first, with the microwave off. A 4,800 W peak unit gives more margin.

Will a 4,000 watt generator run a camper?

• 30 amp camper: yes. A 30 amp RV can draw at most 3,600 W (30 A × 120 V). Most 4,000 W inverters have a TT-30R outlet to plug straight in. Just don't run the AC and the microwave together. See what size generator for a 30 amp RV.
• 50 amp camper: partly. Through an adapter, it runs one AC and the basics, not two ACs. See what size generator for a 50 amp RV.

Will a 4,000 watt generator run a house?

It runs the essentials, with little to spare:

Appliance	Running W	Starting W
Fridge	400	1,200
Sump pump (1/2 HP)	1,000	2,150
Furnace fan (1/3 HP)	700	1,800
Lights, Wi-Fi, chargers, TV	345	same

• Running: 2,445 W
• Biggest surge: the sump pump, 1,150 W
• Starting: 2,445 + 1,150 = 3,595 W

That's under 4,000 starting, so it fits. There's about 850 running watts left: room for a freezer, not a window AC as well.

The 240 V catch. The iGen4000DFc and DF480iX have 120 V outlets and a TT-30R, but no 240 V outlet. That means no 240 V well pump, no central AC, and no 240 V transfer switch hookup. For those, look at a 5,000–7,500 W open-frame model with an L14-30R outlet. See what a 5,000 watt generator can run.

More "will it run" answers

Appliance	On a 4,000 W generator
Refrigerator	Yes. Two fridges, yes
Fridge and freezer	Yes, with lights and Wi-Fi
Gas furnace fan	Yes. An inverter's clean power suits furnace electronics. See generator for a gas furnace
Sump pump, 1/2 HP	Yes
Well pump, 1/2 HP, 120 V	Maybe. Franklin Electric's minimum is 2,000–3,000 W, depending on type
Well pump, 240 V	No, unless the generator has a 240 V outlet
Microwave (1,000 W draw) + fridge	Yes
Space heater (1,500 W) + fridge	Yes
Central AC	No. It's 240 V and needs 3,500+ starting watts even at 2 tons
120 V welder	Borderline. Champion lists 1,800–2,500 running and 3,600–5,000 starting
Air compressor, 1 HP	Unlikely. Honda and Champion list about 4,500 starting
Circular saw, 7-1/4"	Yes (1,400 running, 2,300 starting)

Figures are from Champion's and Honda's charts and our calculator.

Propane and run time

• On propane, output drops. The iGen4000DFc goes from 3,300 to 2,970 running watts; the DF480iX from 4,000 to 3,600.
• Run time: Westinghouse says the iGen4000DFc runs up to 7 hours at 25% load on 1.69 gallons. WEN says the DF480iX runs about 7 hours at half load on 1.9 gallons, or 12 hours at half load on a 20 lb propane tank. See propane tank generator runtime.

Tips to get the most from 4,000 watts

• Start the AC or the biggest motor first, then the rest.
• Turn eco mode off if an AC or fridge start trips the generator.
• One heat maker at a time: microwave, coffee maker, hair dryer or space heater.
• Add a second unit later. Two inverters with a parallel kit act like one bigger generator. See how to run inverter generators in parallel.

Safety: Run it outdoors only, 20+ feet from the house or RV, away from windows, doors and vents. Read our carbon monoxide guide.