Free Generator Sizing Calculator
Estimate the generator size in kilowatts needed to power selected loads during an outage.
W
W
x
Minimum Generator Size
9.0 kW
Running Load5.0 kW
Starting Surge4.0 kW
Minimum Generator Size vs Total Running Watts
Generator Sizing
Minimum kW = Running Watts + Starting Surge
Motors (AC units, pumps, refrigerators) draw 2 to 6 times their running watts during startup. Add the surplus starting watts of the largest motor to the total running watts of everything else.
Example Calculation
5,000W running load, largest motor is 2,000W with 3x starting surge.
- 01Running = 5,000W
- 02Surge = 2,000 x 3 - 2,000 = 4,000W extra
- 03Total = 5,000 + 4,000 = 9,000W = 9.0 kW
- 04Select a 10 kW generator.
Frequently Asked Questions
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