UPS Sizing Calculator
Static · formula-only · worked example computed when this page was built · no live data
The UPS Sizing Calculator picks the UPS kVA rating and reports loading for a critical load and backup time. Example: for a 50 kW critical load on an online double-conversion UPS with 15 min backup, at 0.9 power factor with a 25% design margin, Recommended UPS = 100 kVA, Load = 55.56 kVA, Loading = 55.6 % (per IEEE 1184:2006 | IEC 62040-3:2021 | IEEE 446 | BICSI 002).
How it works
Computed from your inputs per IEEE 1184:2006 | IEC 62040-3:2021 | IEEE 446 | BICSI 002. Anything the worked example does not state uses this calculator's standard default; the interactive version shows every input and lets you change it.
Worked example (Electrical & Power)
Inputs: a 50 kW critical load on an online double-conversion UPS with 15 min backup, at 0.9 power factor with a 25% design margin.
| Result | Value |
|---|---|
| Recommended UPS | 100 kVA |
| Load | 55.56 kVA |
| Loading | 55.6 % |
Computed by WorkHive's calculation engine when this page was built; standard: IEEE 1184:2006 | IEC 62040-3:2021 | IEEE 446 | BICSI 002.
How to use this calculator
- Read the worked example. It uses a 50 kW critical load on an online double-conversion UPS with 15 min backup, at 0.9 power factor with a 25% design margin and shows every number in the method.
- Follow the formula with your own figures: it returns Recommended UPS, Load, Loading, computed per IEEE 1184:2006.
- To compute interactively, open the UPS Sizing Calculator inside WorkHive's free Engineering Design suite (link below). It runs the same method with your inputs.
FAQ
What is a UPS sizing calculator kVA?
The UPS Sizing Calculator is a free online tool that picks the UPS kVA rating and reports loading for a critical load and backup time. It shows the formula and a fully worked example so you can check the method, not just the number.
How is it calculated?
The result is computed from your inputs following IEEE 1184:2006. The worked example on this page shows a real computation with real numbers.
Is the calculator free?
Yes. WorkHive is free: this worked example is open to everyone, and the interactive calculator runs inside the free Engineering Design suite after a free sign-up (your work is saved to your account). WorkHive is a free, offline-first maintenance platform built for Philippine industrial plants.
Run it on your own numbers
Open the interactive UPS Sizing Calculator in WorkHive. Free, and a free sign-up saves your calculations, BOMs and scope-of-works to your account.