UPS sizing calculator

Add your equipment to get the right UPS rating, battery energy and suggested models.

1. Add your equipment

Read the wattage from the device label; defaults are estimates.

DevicePower (W)Qty

Backup time

Power factor

Growth margin

UPS type

Any Online (servers) Line-interactive (office)

First the total load (W) is summed, divided by the power factor to get VA, then a 20–30% margin is added and the next standard rating is selected.

Battery energy = load × time (h) ÷ inverter efficiency and discharge factor. Real backup time depends on temperature, battery age and quality.