Generator Sizing Calculator
Appliance list → required watts and a recommended generator size.
Appliances / circuits to run simultaneously
Appliance
Required running watts
150W
Required starting watts
1,200W
Largest surge: Refrigerator
Recommended generator size
1,500W
What is this tool?
Required running watts is the sum of everything you want to run simultaneously. Required starting watts follows standard generator-sizing logic: only the single largest motor's surge/inrush watts needs to be covered at the moment of startup — everything else is already running at its running watts, not also surging. The recommended size adds a commonly cited ~20% planning buffer on top of the higher of the two totals. Reuses the same appliance presets as the Appliance Running-Cost Estimator so you're not re-typing wattages.
How to use it
- Add each appliance/circuit you want to run at the same time, picking a preset or Custom.
- Adjust running and (optional) starting watts per item as needed.
- Read required running/starting watts and the recommended generator size.
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