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Online Calculator
Battery runtime calculator
Enter capacity in Ah and average current draw in amps to estimate battery life.
It is an idealized estimate. Actual battery life varies with temperature, aging, discharge rate, electronics, and battery type.
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The values are processed directly in your browser.
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Frequently asked questions
What is the basic runtime formula?
Hours ≈ usable Ah / average current.
Why does it include efficiency?
To apply a simple reduction for system losses.
Why does it include usable capacity?
Because using 100% of the rated capacity is not always desirable or possible.
Is that an exact prediction?
No. It is an idealized estimate. Actual battery life depends on many factors.