Home battery backup runtime calculator
Home battery backup runtime calculator
How long a home battery runs your load in a blackout — from usable energy, load, and depth of discharge. Region-agnostic physics, every assumption shown.
Battery
Backup
20 h 15 min
backup at a 2 kW load (100% usable)
40.5kWh
usable energy at 100% DoD
Backup runtime assumes a steady load and ignores inverter/round-trip losses. Whether a battery is worth it financially depends on your state’s tariffs — see the decision page.