This calculator works out inverter VA range from watts, surge, power factor and margin. The recommended VA covers adjusted peak load, power factor and the chosen design margin; it does not determine battery runtime. Replace the example values with information from your own label, bill, drawing, product sheet or land record. Compare the result with both continuous and surge ratings in the manufacturer's datasheet and confirm supported battery-bank voltage. The formula and every editable assumption remain visible so the result can be checked before it is used for planning. Keep the values and result together when you compare or share this planning scenario.
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Motors and compressors can need extra power when they start.
Battery age, temperature and a high discharge rate can reduce delivered energy.
Use this as a planning range. Confirm continuous rating, peak rating and battery compatibility with the manufacturer and a qualified installer.
Read the meaning first, verify the important details, then avoid the most common planning error.
The recommended VA covers adjusted peak load, power factor and the chosen design margin; it does not determine battery runtime.
Compare the result with both continuous and surge ratings in the manufacturer's datasheet and confirm supported battery-bank voltage.
Choosing an inverter from battery Ah alone mixes an energy-capacity measure with a power-capacity decision.
Updated 17 July 2026. Changes listed here describe this calculator release; they are not invented historical entries.