How many watts does a Sump Pump (1/2 HP) use?

A Sump Pump (1/2 HP) draws 1,050 watts continuously once it's running, but its motor needs a brief surge of up to 2,640 watts to start. A generator has to cover that starting surge, not just the running load, or the motor won't start. Based on a real cited 120V nameplate (12A FLA / 22A LRA) for a 1/2 HP sump pump motor — 22A × 120V. Moderate confidence: a professionally-cited real nameplate rather than a manufacturer's own published spec sheet, but real motor data, not a multiplier.

Running it 2 hours/day costs roughly $10.71/month at the U.S. average residential rate (~$0.17/kWh, early 2026, per the EIA) — real rates vary a lot by state and utility. Use your own rate in the House calculator →

Generators that can run this

• Champion 3500-Watt Inverter (100571)
  2,300 W run · 3,500 W start · ~$699
• Honda EU3200i
  2,600 W run · 3,200 W start · ~$2,799
• Champion 4000W Dual Fuel Inverter (201050)
  3,000 W run · 4,000 W start · ~$749

Prices as of July 2026 — check the current listing before buying.