Inverter Battery Draw Calculator

Running a 240V appliance off the battery? See what it really takes from the battery.

An inverter turns battery power into 240V AC, and loses some energy doing it. This works out the DC current and energy taken from the battery. Everything is worked out in your browser. Nothing is saved or sent anywhere.

1. The appliance

Use the watts on the appliance label or a plug-in power meter reading.

Per day.
Often 85 to 92% at a decent load. Lower at light loads.

2. Your battery

3. Results

How it was worked out

    What this does and doesn't tell you

    • Appliances with motors or compressors can draw several times their running watts for a moment when they start. The inverter must handle that surge.
    • Inverters also draw some power just being switched on. Turn it off when you are not using it.
    • Check cable and fuse sizes for this current with the Cable Size Estimator and Fuse Size Calculator.
    • Work on 240V AC wiring, including inverter outputs and mains inlets, must be done by a licensed electrician. For high-current DC gear, follow the maker's installation manual and have an auto electrician check your work if you're unsure.
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