How to choose a right UPS power supply for your home,office, business, Server Room or Data Center Facility? If you understand the basics, this is not difficult.

UPSs are given a power rating in volt-amperes (VA) that range from 300 VA to 5,000 kVA. This rating represents the maximum load that a UPS can support, but it shouldn't match exactly the power load you have. In fact, you need the following steps to size UPS.

First step:Gathering load data and divide by 0.8

If you have the total load (kW), divide by power factor of UPS （usually 0.8） to get the kVA and move on the second steps.

Seconde step: About the redundacy

To allow room for growth, UPS, you may want some redundancy 30% ,for example, instead of full load so you need to divide the calculation result by (100%-30%=80%).

Then you can finally get the right capacity of the UPS.