UPS Runtime Calculator
Enter battery capacity, battery voltage, load, and estimated inverter efficiency for an approximate runtime.
A QUICK WALKTHROUGH
How to use this tool
- Enter capacity in Ah, voltage in V, load in W, and efficiency.
- Calculate nominal runtime in hours and minutes.
- Treat the result as an estimate, not a guaranteed runtime.
Estimate only
Runtime = Ah × V × efficiency ÷ load W. Actual UPS runtime varies with battery age, temperature, discharge curve, cutoff, wiring, and changing load.
Input boundary
Use finite positive capacity, voltage, and load values. Efficiency must be greater than 0% and no more than 100%.
Local calculation
The estimate runs in your browser; values are not uploaded or stored.
GOOD TO KNOW
Common questions
Is this a UPS guarantee?
No. It is a nominal estimate and should not replace the UPS manufacturer runtime chart or a measured test.
Why is real runtime shorter?
Usable capacity, inverter behavior, cutoff voltage, aging, temperature, and load peaks reduce runtime.
What load should I enter?
Use the real watts consumed by the protected equipment, including power supplies and conversion losses where appropriate.