GeneratorCalc
Simple calculators for backup power & energy use
Free tools • No signup • No data saved

Quick summary

This calculator adds up running watts and starting watts for the appliances you want to run on a generator.

It helps you compare total running load and surge load so you can choose a generator size with enough capacity.

GeneratorCalc
Simple calculators & guides for backup power
Free tools • No signup • No data saved

Starting vs running watts calculator for generators

Many motor-driven appliances draw more power for a few seconds when they start.

Use this calculator to add up running and starting watts across several loads so you can pick a generator that can handle the combined surge.

Starting vs running watts

List a few appliances and compare total running watts to estimated starting (surge) watts.

Enter up to five appliances. If you do not know starting watts, the calculator can assume about 2× running watts as a rough default.

For more planning tools, you can also use the other calculators and guides on the GeneratorCalc home page.

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These tools are for planning and estimation only. They do not replace manufacturer specifications, local codes, or professional advice. Always follow your generator manual and consult a qualified professional for permanent installations or whole-home backup systems.

GeneratorCalc is reader-supported. As an Amazon Associate, we earn from qualifying purchases made through links on this site.

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