Generator Size for a Sump Pump
Find the right generator for a sump pump. Enter its running and startup watts to see the recommended generator size, with headroom for the motor surge.
Runs locally in your browser — no upload, no trackingTry: Sump pump running watts=800, Sump pump startup (surge) watts=1800 → 800 W, 1,800 W, 2,160 W, 3.5 kW
How to use
A ½ HP sump pump draws about 800 running watts and surges to 1,800 on start. During a storm outage the pump may cycle often, so size for the surge, not the steady draw. Enter your appliance's running and startup (surge) watts and press Calculate. The recommended size adds a 20% safety margin to the surge so the generator is never running at its limit.
These are typical figures — the plate on your sump pump may read differently. If you run more than one device together, use the multi-appliance calculator instead.
FAQ
What size generator will run a sump pump?
A ½ HP sump pump needs about 800 running watts and 1,800 starting watts. A 3 kW generator covers the pump, but add more capacity if it shares the generator with a fridge or furnace.