Generator Size Calculator

One per line. Leave off starting watts for things without a motor. Use the label or manual for exact numbers.

%

Extra capacity so the generator is not running flat out.

Running watts needed

3,925 W

Starting (surge) watts needed
5,425 W
Running watts with 20% headroom
4,800 W
Starting watts with 20% headroom
6,600 W
Largest starting load
Refrigerator
Current at 240 V (running)
16.4 A
Refrigerator: 700Sump pump (1/2 hp): 1,050Furnace fan (1/2 hp): 875Lights (10 LED bulbs): 100Microwave: 1,000TV and Wi-Fi router: 200
RefrigeratorTV and Wi-Fi router

Look for a generator whose running (rated) watts and starting (peak) watts both meet these numbers. Never run a generator indoors, in a garage or near windows: its exhaust contains deadly carbon monoxide.

Your list6 rows
ApplianceRunning WStarting W
Refrigerator7002,200
Sump pump (1/2 hp)1,0502,150
Furnace fan (1/2 hp)8752,350
Lights (10 LED bulbs)100100
Microwave1,0001,000
TV and Wi-Fi router200200

Open the full generator size calculator with the formula and FAQs at Calcs for Life