Generator Sizing Calculator
Figure out what size generator you need. Check off the appliances you want to keep running during an outage — the calculator adds their running watts plus the single largest startup surge and recommends a generator size.
Pick what you want to keep running
Recommended generator
6.9 kW
≈ 6,900 W starting capacity
- Running watts (all on)
- 4,150 W
- Peak with largest surge
- 5,700 W
Sized as running watts plus the single largest motor surge, with ~20% headroom. Wattages are typical — check your appliances' labels. A portable generator needs a manual transfer switch or interlock; never back-feed an outlet. Have an electrician handle the connection.
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Open calculatorSources & standards
This tool's methodology and data follow US standards and authoritative public datasets: