What is the UPS Runtime Calculator?
Estimate backup runtime from nominal battery energy and a constant connected load.
This simplified energy model cannot reproduce a manufacturer discharge curve at every load.
Formula and calculation method
runtime hours = voltage × Ah × batteries × usable depth × efficiency ÷ load watts.
The calculation runs locally in your browser and uses only the values entered on this page.
Important limitations
Technology estimates simplify real systems. Hardware, software, network conditions, measurement conventions and manufacturer behavior can change actual results.
Planning scope: Use the result as an estimate and confirm critical sizing or configuration with current product documentation.
UPS Runtime Calculator FAQs
Manufacturers model battery discharge rate, inverter behavior and specific hardware.
Enter the real connected load in watts.
Yes. Older or warm batteries can provide less usable energy.
No. Results are educational estimates based only on the values and simplifying assumptions entered.
Yes. A displayed result is hidden as soon as an input changes so an old answer is not mistaken for a current calculation.
Yes. The form, colorful result panel and calculation steps are responsive for phones, tablets and desktops.
Sources and methodology
Official source links support terminology and measurement context. The arithmetic runs locally in your browser.