Size a UPS for a connected load with headroom and power factor accounted for.
UPS units are rated in kVA but loads are specified in watts, so power factor must be applied. Running above about 80 per cent of nameplate shortens both battery and electronics life. A UPS loaded above 90 per cent has no capacity for the inrush of a restarting load, which is when it is most likely to be needed.
UPS Load
UPS kVA = load ÷ power factor × (1 + headroom) ÷ maximum loading
UPS kVA = load ÷ power factor × (1 + headroom) ÷ maximum loading UPS units are rated in kVA but loads are specified in watts, so power factor must be applied. Running above about 80 per cent of nameplate shortens both battery and electronics life.
A UPS loaded above 90 per cent has no capacity for the inrush of a restarting load, which is when it is most likely to be needed.
This calculator takes 4 inputs: Connected load, Load power factor, Headroom for growth, Maximum continuous loading. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.