698 tools
All

Generator Watts Calculator

Running watts from a list of loads, plus a surge percent for starting.

%

 

Running W
Surge W

About this calculator

Use this calculator to size a portable generator from the nameplate watts of the things you will run together.

Running watts are the sum of the loads. Surge watts are running × (1 + surge percent). 100 + 1500 + 800 W is 2 400 W running. 25% surge is 3 000 W. Motors want a larger surge than LEDs. Nameplate starting watts beat a flat percent when you have them. Negative loads are summed as written.

Loads (W): Watt draws, comma or space separated.

Surge: Extra percent for starting loads. Type 25 for 25%.

Running W: Continuous total.

Surge W: Starting total with the percent applied.