A load with an apparent power of 5 kVA at 100V draws 50 amps (single-phase). Generators, UPS systems, and transformers publish kVA ratings because the circuit current on the output is set by apparent power, not by the load's real-power draw. This conversion gives you the apparent-power current so you can size breakers and wiring.
Assumes a single-phase AC circuit at the input voltage. kVA is apparent power, so no power factor term is involved.
Formulas
Single Phase
I(A) = (kVA × 1000) ÷ V
(5 × 1000) ÷ 100 = 5,000 ÷ 100 = 50 A
Generator & UPS Sizing
Load-Side Real Power by Power Factor
A load with an apparent power of 5 kVA draws different amounts of real power depending on the load's own power factor. The table below is a load-side conversion, not a forecast of what a generator or UPS will output for that load: generators and UPS units publish their own independent kW rating set by the engine or inverter design, and that rating is often lower than kVA × the load's PF.
Load Type
Load PF
Load Real Power (kW)
Current at 100V
Resistive (heaters, lights)
1.0
5 kW
50 A
Mixed typical
0.85
4.25 kW
50 A
Motors/HVAC
0.80
4 kW
50 A
Computers/servers (no PFC)
0.65
3.25 kW
50 A
Note: current draw stays the same across the rows because kVA sets the current, not the load's power factor. PF only affects how much real work (kW) the load does per amp drawn.
Sizing a load against a source. If you are feeding this load from a UPS, generator, or transformer, check the load against both the source's kVA rating AND the source's kW rating. Those are two independent numbers published by the manufacturer. A 10 kVA / 8 kW generator, for example, can supply up to 10 kVA of apparent power AND up to 8 kW of real power, whichever limit is reached first. Do not use the kW figures above as a substitute for the source's published kW rating.
Circuit Sizing: Starting Points
The numbers below are rough order-of-magnitude starting points under typical assumptions (copper conductors, 75°C terminations, short run, no ambient or bundling derates, non-continuous duty). They are not install specs. Actual breaker and wire selection depends on the equipment nameplate, conductor and termination temperature ratings, cable type, run length and voltage-drop target, ambient and bundling conditions, whether the load is continuous, any NEC 430/440 motor or HVAC provisions, and local code.
Single Phase
Current draw (at full kVA)
50 A
Ballpark branch OCP
~50A
For a real install, run the full wire-size calculator with your actual run length, voltage, and drop target, and verify breaker selection against the equipment nameplate and local code.
Energy Cost at Full Load
A load with an apparent power of 5 kVA at load PF 0.85 draws 4.25 kW of real power. Running cost at that draw: $0.72/hour at $0.17/kWh (rates last reviewed April 2026), or $173.40/month (8h/day). Full breakdown.
5 kVA at 100V is 50 amps (single-phase). 100V is a single-phase voltage; three-phase configurations are not typical at this voltage.
Generator sizing is not a single-formula calculation. A rough napkin pass is: add up the steady-state watts of everything you plan to run, divide by a planning power factor (often 0.8 but not universal), and add margin. Then cross-check the result against the generator's published kW rating, which is a separate manufacturer spec set by the engine (prime mover) and is not derived from the generator's kVA rating by any formula. The caveats that matter for a real install: motor and compressor inrush can be several times steady-state current, load diversity and sequencing affect peak demand, voltage-dip tolerance of sensitive equipment limits how much motor load a given genset can start, and altitude and ambient temperature both derate output. A load with an apparent power of 5 kVA at PF 0.8 has a real-power draw of 4 kW, but that number alone is not sufficient to size a generator for a real installation.
Because the current on the output (and therefore the conductor, switchgear, and winding sizing) is set by apparent power, kVA = V×I, regardless of the load's power factor. UPS and generator manufacturers publish a separate kW rating in addition to the kVA rating, set by the inverter or engine design, and it is often lower than the kVA rating. You cannot derive a UPS or generator's kW output from its kVA rating and the load's power factor: the two ratings are independent specs and a load has to fit under each of them when sizing against the source.
kVA is apparent power (V×I), which sets the current on the circuit and the sizing of conductors, breakers, and windings. kW is real power (the portion that does useful work), equal to kVA×load PF. A load with an apparent power of 5 kVA at load PF 0.8 draws 4 kW of real power. For a source such as a generator or UPS, kVA and kW are two independent manufacturer ratings, not two views of the same spec, and both have to be checked when sizing a load.
Fuel burn is set by the generator's specific-fuel-consumption curve, not a rule of thumb tied to the kVA rating. It varies sharply with fuel type (gasoline vs diesel vs natural gas vs propane), load percentage (partial-load efficiency is much worse than full-load), engine size and age, altitude, and ambient temperature. For a specific unit, check the manufacturer's fuel-consumption curve at your expected load percentage. Generic per-hour estimates from the kVA rating alone are not reliable enough to plan fuel capacity from.
This calculator provides estimates for reference purposes only. Always consult a licensed electrician and verify compliance with the National Electrical Code (NEC) and local electrical codes before performing any electrical work.
