Short answer: Use roughly 2× the microwave's cooking watts: a 1,000 W microwave usually draws 1,400–1,700 W from the outlet, so pick a 2,000 W pure sine wave inverter.
| Microwave (cooking W) | Input W (approx.) | Inverter | 12V DC amps |
|---|---|---|---|
| 700 | 1100 | 1,500 W | 102 A |
| 1000 | 1550 | 2,000 W | 144 A |
| 1200 | 1800 | 2,500–3,000 W | 167 A |
Check the input watts on the label inside the door. Ten minutes at 1,550 W is ~260 Wh, so short use is fine on a modest lithium bank if it can supply ~145 A.
Safety: These are general estimates, not a design. Follow your equipment manufacturer's instructions and local electrical code, and consult a qualified electrician for anything connected to shore power, a house, or high-current batteries.
Only very small (600–700 W cooking) microwaves, and even then often not; 1,500–2,000 W is safer.
Yes, modified sine wave inverters make microwaves run hot, noisy and less efficient.
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