Quick answer
Generator size should cover your simultaneous running watts and enough startup headroom for the largest motor-driven load you expect to start. The right answer is therefore based on the appliances you will actually run together, not on house size alone.
How to work it out
- List only the devices you expect to power at the same time.
- Add their running wattage.
- Identify the largest additional startup/surge requirement.
- Add that surge to the running load.
- Choose a generator with additional operating headroom rather than targeting 100% continuous load.
Example
If your selected loads total 4,200 running watts and the largest startup event adds 1,800 watts, the immediate requirement is about 6,000 watts before any additional operating margin.
What can change the answer
Electrical connection, transfer equipment, fuel storage, ventilation and carbon-monoxide safety require manufacturer and professional guidance.
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