Selected load details
Edit watts, surge, and usage hours
Refrigerator
Wi-Fi and modem
LED lights
Phones and tablets
Search intent
home battery runtime calculator
Sizing a battery, power station, or generator before requesting quotes.
Use this when
- Estimate how long a battery can run a refrigerator, Wi-Fi, lights, sump pump, or medical device.
- Compare 3 kWh, 5 kWh, 10 kWh, 13.5 kWh, and 20 kWh battery sizes against the same essential-load list.
- Turn outage-hour assumptions into a first-pass kWh and inverter wattage target.
- Compare portable power stations, home batteries, and generators with the same load list.
Estimate model
What this calculator uses
- Selected appliances, running watts, surge watts, and daily use hours
- Target outage duration and reserve margin
- Battery efficiency before converting load into recommended kWh
- Runtime estimates for common battery sizes using the same repeated daily schedule
Quote readiness
Checks before you call a contractor
- Ask whether the quote backs up exact circuits or only plug-in loads.
- Confirm usable battery capacity, inverter surge rating, and reserve settings.
- Ask installers to show the average draw, daily schedule, and surge-start assumptions behind their runtime claim.
- Price transfer equipment, gateway, permits, and critical-load panel work separately.
Official verification
Sources to check before budget decisions
Use official outage guidance for preparedness, then verify any storage incentive against 2026 federal, state, utility, and DSIRE sources before reducing the budget.