Free calculator

Home Battery Sizing Calculator

Estimate the usable kWh you need for an outage, compare common battery sizes, and see when a portable power station may be enough.

Load profile

What should stay on?

Refrigerator and freezerEdit the kWh/day if you know your real usage.kWh/day

LED lightsEdit the kWh/day if you know your real usage.kWh/day

Wi-Fi, phones, laptopEdit the kWh/day if you know your real usage.kWh/day

Small outlets and kitchen basicsEdit the kWh/day if you know your real usage.kWh/day

Medical device / CPAPEdit the kWh/day if you know your real usage.kWh/day

Sump pump cyclesEdit the kWh/day if you know your real usage.kWh/day

Well pump cyclesEdit the kWh/day if you know your real usage.kWh/day

Limited HVAC / heat pump runtimeEdit the kWh/day if you know your real usage.kWh/day

How to use the result

Treat the calculator as a buyer screen, not an electrical design. The important number is usable kWh for the loads you actually need during an outage. A good quote should name those loads and show whether the design is whole-home backup, essential-load backup, or something smaller.

If the result is under a few kWh, read the portable power station guide before spending on a permanent system. If the result needs one or more wall batteries, move to the quote benchmark calculator.