UPS Calculator
Estimate minimum VA and a suitable UPS capacity from load and power factor.
Runtime in minutes requires real battery and efficiency data; this tool does not invent that figure.
What this tool does
The UPS/SAI estimate helps size a backup unit for the equipment you plan to connect. Wattage alone does not determine runtime: battery capacity, inverter efficiency, power factor and battery age all affect how long the system can stay on.
How to use it
Enter the values requested by the calculator and check the result together with the notes shown below it.
Practical example
Use a realistic example from your own setup to compare scenarios. The result is a reference, not a replacement for manufacturer specifications.
How to interpret the result
Treat the result as an estimate whenever real-world factors are not available to the browser. For hardware, network or safety decisions, verify the relevant technical specifications.
Frequently asked questions
What is the difference between watts and VA?
Watts are real power and VA is apparent power. They are linked by the power factor, which is why a UPS is sized in VA.
How much headroom is advisable?
A 20–30 % margin over the load avoids running at the limit and leaves room to expand your equipment.