Battery Runtime Calculator
Estimate battery runtime from capacity, voltage, and load, with depth-of-discharge and efficiency factors.
Processed locally in your browser — nothing is uploaded.
~50% for lead-acid, 80–90% for LiFePO4.
Inverter and wiring losses; ~90% is typical.
Results
- Estimated runtime
- 14h 24m
- Runtime (decimal hours)
- 14.4 h
- Usable energy
- 960 Wh
- Load
- 60 W
Real capacity shrinks at high discharge rates (Peukert effect), low temperatures, and with battery age — treat this as an upper-bound estimate.
About Battery Runtime Calculator
Multiply capacity by voltage for watt-hours, keep only the usable depth-of-discharge fraction, apply inverter efficiency, and divide by the load: that's the runtime this tool computes, shown in hours and minutes. Capacity can be entered in Ah or mAh and the load in watts or amps.
Common uses
- Estimate how long a 100 Ah LiFePO4 battery runs a 12 V fridge
- Size a power-station purchase for a CPAP machine or laptop
- Sanity-check a camper or boat house-battery plan
Example
Input
100 Ah · 12 V · 60 W load · 80% DoD · 90% efficiency
Output
≈ 14 h 24 m
Limitations
- High discharge rates, cold temperatures, and battery age all reduce real capacity (Peukert effect) — treat results as an upper bound.