Inverter Size Calculator

Find the continuous and surge rating your inverter needs, and how much current it draws from the battery.

Watts from nameplates.
–
Continuous rating
Surge rating needed
DC input current
Note
Work

Saved Calculations

Items you add are saved in this browser.

NameCalculationResultRemove

How to Size an Inverter

Continuous rating ≥ total running watts × (1 + margin)   Surge rating ≥ largest starting watts
DC current = AC watts ÷ efficiency ÷ battery volts

Worked Example

Tips

Motors, compressors and pumps can draw 2 to 3 times their running watts to start. Pure sine wave inverters are best for electronics and motors. Fuse the DC cable close to the battery.