Enter your battery capacity, voltage and load to estimate the runtime — with depth of discharge and efficiency built in.
This battery runtime calculator estimates how long a battery will power a load. First it finds the energy in watt-hours — for an Ah battery that's Ah × voltage. Then it applies the usable depth of discharge (you rarely use 100%) and an efficiency factor for inverter and heat losses, and divides by the load in watts: runtime = Wh × DoD × efficiency ÷ load. Use it for UPS backup, solar storage, camping, RVs and off-grid setups.
Battery chemistry matters: lead-acid lasts longest at about 50% DoD, while lithium (LiFePO4) handles 80–90%. Running through an inverter costs roughly 10–15% efficiency. Setting these honestly gives a runtime you can trust rather than the theoretical maximum.
Related: Ohm's Law Calculator · Wire Size Calculator