Generator Size Calculator
Choose a generator size from running and starting loads.
W
W
%
How it works
Required watts = (running watts + the extra surge of the biggest motor) × (1 + margin). Motors such as air conditioners and pumps can draw 2–3 times their running power for a second or two at start. kVA = watts ÷ 1000 ÷ power factor. Example: with the default values, recommended generator size comes to 9,000 W.
FAQ
Is this calculator free?
Yes. No signup is needed and nothing you enter is stored.
Is the result exact?
Results are rounded for display. For financial, medical, or legal decisions, confirm with a professional.
Do my numbers leave my device?
No. The calculation runs in your browser.