What Size Generator Do I Need to Run a Microwave?

Honda lists three cooking sizes, and the largest one sets the generator.

Quick answer: Honda lists a 1,000 W microwave at 1,500 running watts and 1,500 starting watts (a 650 W oven is 1,000 W and an 800 W oven is 1,300 W), and Champion lists 600–1,200 watts with no separate start. Covering the 1,000 W oven takes ratings that clear 1,500 W running and 1,500 W starting. A Honda EU2200i rated at 1,800 W, with a 2,200 W maximum, covers that oven.

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Running and starting watts

Load	Running watts	Starting watts	Source
Microwave, 650 W cooking	1,000	1,000	Honda
Microwave, 800 W cooking	1,300	1,300	Honda
Microwave, 1,000 W cooking	1,500	1,500	Honda
Microwave	600–1,200	Not listed	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.

Honda lists the same number for start and run on each microwave, so do not add a second surge. Champion does not list a separate start either. Honda notes that an inverter converts AC to DC and back to AC, which gives lower THD than a conventional generator that runs at full RPM.

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

How many watts does a 1,000 W microwave pull from the generator?

Honda lists 1,500 running watts and 1,500 starting watts. The 1,000 W figure is the cooking rating, not the generator load.

What about a smaller microwave?

Honda lists a 650 W microwave at 1,000 W running and starting, and an 800 W microwave at 1,300 W running and starting.

Is Champion's range a start or a run figure?

The chart lists 600–1,200 and no separate start. Treat it as running watts and do not invent a surge.

Can the EU2200i run the largest oven on this chart?

Yes. 1,500 W is under the EU2200i rated output of 1,800 W and under the 2,200 W maximum.