Inverter Sizing Calculator
Minimum inverter rating for a set of AC loads.
Enter your values
ⓘ Live results
Results
- Minimum continuous rating
- 960 W
- Minimum surge rating
- 1650 W
- Recommended inverter size
- 1650 W
Quick answer
Inverter continuous rating should exceed total running watts x safety margin.
Inverter rating >= total load x margin
How to use the Inverter Sizing Calculator
- 1Add up the running wattage of all devices to run simultaneously.
- 2Identify the single largest surge load (motors and compressors draw 2-3x their running watts at startup).
- 3Choose an inverter that comfortably covers both figures with margin.
Worked example
Using the values the calculator loads with:
Inputs
- Total running load800 W
- Largest surge/starting load1500 W
- Safety margin20 %
Results
- Minimum continuous rating960 W
- Minimum surge rating1650 W
- Recommended inverter size1650 W
Frequently asked questions
Why is surge rating important?
Motors, pumps and compressors need a brief high-current surge to start; an undersized inverter will trip or fail.
Pure sine vs modified sine?
Sensitive electronics and motors run better and last longer on pure sine wave inverters.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.