Power & UPS Tool

UPS Runtime Calculator

Estimate backup runtime for UPS systems using load, battery capacity, voltage, efficiency and reserve margin.

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UPS Runtime

Runtime input

Enter the UPS load and battery details. Runtime is estimated automatically.

Connected load

UPS power factor Battery string voltage

V DC

Battery capacity

Number of battery strings UPS efficiency

Usable battery capacity

Reserve margin

Formula used

Runtime ≈ (Battery V × Ah × strings × usable capacity × efficiency × reserve factor) ÷ load W

Planning note

Runtime estimates depend heavily on battery condition, UPS model, discharge curve and temperature.

How to use this calculator

1. Enter load

Use estimated or measured load in watts for the protected equipment.

2. Add battery data

Enter battery string voltage, Ah capacity and number of strings.

3. Review runtime

Check estimated runtime and apply conservative planning margin.

Learn more

UPS — Wikipedia Ampere-hour — Wikipedia Volt-ampere — Wikipedia

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Disclaimer: This calculator is provided for planning and educational purposes only. UPS runtime depends on battery condition, discharge curves, UPS topology, temperature, age, load profile and manufacturer-specific behavior. Always verify critical power designs with vendor runtime charts, qualified electrical review and site requirements.