Generator Sizing Calculator
Static · formula-only · worked example computed when this page was built · no live data
The Generator Sizing Calculator finds the standby genset kVA for a load, accounting for the largest motor's starting kVA surge. Example: for a 100 kW load with a 20 HP DOL-started largest motor, Recommended genset = 250 kVA, Steady demand = 129.41 kVA, Peak during start = 215.16 kVA (per ISO 8528-1:2018 | ISO 3046-1 | IEEE 446 | PEC 2017 | NFPA 110).
How it works
Computed from your inputs per ISO 8528-1:2018 | ISO 3046-1 | IEEE 446 | PEC 2017 | NFPA 110. 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 100 kW load with a 20 HP DOL-started largest motor.
| Result | Value |
|---|---|
| Recommended genset | 250 kVA |
| Steady demand | 129.41 kVA |
| Peak during start | 215.16 kVA |
Computed by WorkHive's calculation engine when this page was built; standard: ISO 8528-1:2018 | ISO 3046-1 | IEEE 446 | PEC 2017 | NFPA 110.
How to use this calculator
- Read the worked example. It uses a 100 kW load with a 20 HP DOL-started largest motor and shows every number in the method.
- Follow the formula with your own figures: it returns Recommended genset, Steady demand, Peak during start, computed per ISO 8528-1:2018.
- To compute interactively, open the Generator Sizing Calculator inside WorkHive's free Engineering Design suite (link below). It runs the same method with your inputs.
FAQ
What is a genset sizing calculator kVA?
The Generator Sizing Calculator is a free online tool that finds the standby genset kVA for a load, accounting for the largest motor's starting kVA surge. 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 ISO 8528-1:2018. 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 Generator Sizing Calculator in WorkHive. Free, and a free sign-up saves your calculations, BOMs and scope-of-works to your account.