kW to kVA Calculator
How many kVA a load of a given kW needs, from the power factor.
The formula
kVA = kW / PF
An 80 kW load at power factor 0.8 needs 100 kVA. Undersizing is the classic generator mistake: the set must supply the full volt-amps, not just the watts.
Sizing rules of thumb
Size a generator or UPS on kVA first, then check the kW rating separately, since most sets have both limits. Add 20 to 25% headroom over the calculated figure, and more if large motors start direct-on-line: starting inrush can be 6 times running current for a few seconds, which small generators cannot ride through.