What Size Generator Do I Need to Run a Pressure Washer?
Match the row to the washer you own, whether that is the horsepower line or the psi lines.
Affiliate disclosure: as an Amazon Associate, we earn from qualifying purchases — at no cost to you.
Running and starting watts
| Load | Running watts | Starting watts | Source |
|---|---|---|---|
| Pressure washer, 1 hp | 1,200 | 3,600 | Honda |
| Pressure washer, 1,500 psi | 1,200–1,500 | 2,400–3,000 | Champion |
| Pressure washer, 2,500 psi | 2,000–2,500 | 4,000–5,000 | Champion |
Honda's wattage guide lists starting watts, then running watts. Champion's chart lists running watts, then starting watts. This table puts every figure in the Running and Starting columns. Not listed means that source does not give a separate starting figure.
How to size it
Add the running watts of every load that will be on together, then add the single highest starting surge (Generac; Honda). Generac notes that starting watts are often 2–3 times running watts, and that standby units should get a dealer survey.
A 1,500 psi washer is the middle row: Champion lists 1,200–1,500 running watts and 2,400–3,000 starting watts. Honda's 1 hp start of 3,600 W is above that 1,500 psi start and below the 2,500 psi start of 5,000 W. Pick the row that matches the machine, then use the higher figure only when you want one generator that covers every row.
Check a full load list on the generator size calculator.
Run the generator outdoors only, 20 ft from the house (CPSC).
FAQ
What does Honda list for a 1 hp pressure washer?
1,200 running watts and 3,600 starting watts.
What does Champion list at 1,500 psi?
1,200–1,500 running watts and 2,400–3,000 starting watts.
What does Champion list at 2,500 psi?
2,000–2,500 running watts and 4,000–5,000 starting watts.
Will a 6,250 W starting rating cover the 2,500 psi row?
Yes. The manual lists 6,250 W starting and 5,000 W running. The row tops out at 5,000 W starting and 2,500 W running.
Related questions
- What size generator for an air compressor
- What size generator for a table saw
- What size generator for a 120 V welder
All of these questions are listed on the topic map.