Battery Life Calculator
A free, browser-based calculator. Runs entirely in your browser — no sign up, nothing stored.
100% FreeRuns in your browserBasic
Enter Values
Enter your values and press Calculate to see results.
How to use this calculator
- Enter the battery capacity in amp-hours and the load current in amps.
- Press Calculate for the runtime.
How it works
Runtime ≈ capacity (Ah) ÷ load (A). This is an ideal figure — usable runtime is lower because most batteries shouldn't be fully discharged.
Worked example
100 Ah at 5 A. 100 ÷ 5 = 20 hours (ideal).
Related tools
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.