What Size Generator Do I Need to Run a 120 V Welder?

This page sizes the lower-voltage welder row. The higher-voltage row is only a comparison.

Quick answer: Champion lists a 120 V welder at 1,800–2,500 running watts and 3,600–5,000 starting watts. Covering that row takes a running rating that clears 2,500 W and a starting rating that clears 5,000 W. The Champion manual lists 5,000 W running and 6,250 W starting, which covers the 120 V row, while the same chart's 240 V welder is listed at 3,000–8,000 running watts and 6,000–16,000 starting watts, past that manual's 5,000 W running and 6,250 W starting figures at the top of the range.

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Running and starting watts

Load	Running watts	Starting watts	Source
Welder, 120 V	1,800–2,500	3,600–5,000	Champion
Welder, 240 V (comparison)	3,000–8,000	6,000–16,000	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.

The 240 V numbers are a comparison, not the target of this page. Two EU2200i units in parallel reach only up to 4,400 W. A 120 V running load up to 2,500 W fits under that ceiling. A 120 V start up to 5,000 W does not.

Check a full load list on the generator size calculator.

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Run the generator outdoors only, 20 ft from the house (CPSC).

FAQ

What size generator for a 120 V welder?

Clear 2,500 W running and 5,000 W starting. The manual lists 5,000 W running and 6,250 W starting.

What is the 240 V welder on the same chart?

Champion lists 3,000–8,000 running watts and 6,000–16,000 starting watts. That top end is above the 5,000 W running and 6,250 W starting figures in the manual.

Can parallel EU2200i units run the 120 V row?

Running watts up to 2,500 W fit under 4,400 W. Starting watts up to 5,000 W do not.

Does Honda list a welder?

Not in the wattage guide used here. The welder rows are Champion's only. A 10-inch table saw on Honda's chart is a separate tool at 4,500 W starting.