Free Inverter Size Calculator
Use this free inverter size calculator to find the right inverter wattage for your solar system, RV, van, or home backup setup. Enter the AC appliances you want to run, add their running watts and surge watts, and the calculator will estimate your recommended inverter size plus the battery capacity needed for your selected runtime.
⚡ Inverter Size Calculator
List your AC devices — enter running watts and whether they run simultaneously
AC Device
Running W
Surge W
Simultaneous?
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Simultaneous load
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Inverter size needed
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Min surge capacity
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Battery for runtime
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After calculating your inverter size, always choose a pure sine wave inverter and check both the continuous watt rating and surge watt rating. For best results, add a 20–25% safety buffer above your total running watts and make sure your battery bank can support the runtime you need without excessive current draw.