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Battery and UPS runtime calculator

Estimated runtime from battery capacity, voltage and load.

Ah
V
W
%
Lead-acid ≈50–80%, lithium ≈80–90%
%
100% for a DC load

Calculating…

How it's calculated

Runtime = Ah × V × DoD × η ÷ load W

This is an ideal estimate. Real runtime is shorter at high discharge rates, especially for lead-acid (Peukert effect), in the cold and as batteries age. A lead-acid battery rated at 100 Ah over 20 hours may deliver only 60–70 Ah when discharged in one hour.