kVA to kW converter for single- and three-phase power
Generators, UPS units and transformers are rated in kVA, loads and electricity meters count kW, capacitor banks are sold in kVAR and cables are chosen by amps. This kVA to kW converter moves between all four for a single-phase or three-phase supply: enter one value, the power factor and the voltage, and it shows the apparent, real and reactive power, the current per line, the phase angle and every formula with your numbers.
Two optional extras cover the questions that usually follow: how much capacitor kVAR would raise the power factor to a target, and how big a diesel generator (DG set) the load needs once you add a safety margin. The defaults suit Indian and European 415 V three-phase supplies; type 400, 480 or 208 V, or switch to single-phase 230 or 120 V. Results are estimates for planning, not a design sign-off.
How to use the kVA to kW Converter
- Choose Three-phase or Single-phase.
- Under Convert from pick what you know — kVA, kW, amps or kVAR — and type the value.
- Enter the power factor (or tap a typical value) and the voltage: line-to-line for three-phase.
- Optionally add a target power factor for the capacitor kVAR, and a generator margin.
- Read kVA, kW, kVAR and amps with the steps, check the chart of common sizes, and copy the results.
kVA to kW Converter features
Four starting points
Convert kVA to kW, kW to kVA, amps to kVA and kW, or kVAR to kVA, all at the same power factor.
1 and 3 phase
S = V × I for single-phase and √3 × V × I with the line-to-line voltage for three-phase.
Power factor correction
Capacitor kVAR = kW × (tan φ₁ − tan φ₂), with the kVA and current after correction.
Generator check
A set rated at 0.8 PF must cover both the kVA and kW ÷ 0.8; your margin goes on top.
Size chart
kW and amps for 5 to 1,000 kVA at your voltage, recalculated as you type.
kVA to kW formula (and back)
Real power, reactive power and apparent power form a right-angled triangle: kVA² = kW² + kVAR². The power factor is the cosine of the angle between kVA and kW, so kW = kVA × PF, kVA = kW ÷ PF and kVAR = √(kVA² − kW²) = kVA × sin φ. These are the standard definitions for sinusoidal, balanced supplies (as set out in IEEE Std 1459).
Current comes from the kVA, not the kW. Single-phase: I = kVA × 1,000 ÷ V. Three-phase with the line-to-line voltage: I = kVA × 1,000 ÷ (√3 × V). Example: 100 kVA at PF 0.8 on 415 V three-phase is 80 kW and 60 kVAR, drawing 100,000 ÷ (1.732 × 415) = 139 A in each line. The same 100 kVA at 480 V draws 120 A.
| You know | Single-phase | Three-phase (V line-to-line) |
|---|---|---|
| kVA → kW | kW = kVA × PF | kW = kVA × PF |
| kW → kVA | kVA = kW ÷ PF | kVA = kW ÷ PF |
| Amps → kVA | kVA = V × I ÷ 1,000 | kVA = √3 × V × I ÷ 1,000 |
| kVA → amps | I = kVA × 1,000 ÷ V | I = kVA × 1,000 ÷ (√3 × V) |
| kVAR | kVAR = √(kVA² − kW²) | kVAR = √(kVA² − kW²) |
Sizing a generator or DG set in kVA
Generator sets are conventionally rated in kVA at a lagging power factor of 0.8 (the rating basis in ISO 8528-1), so a 125 kVA set can deliver at most 100 kW. The engine limits kW and the alternator limits kVA, so the set must cover both: required kVA = the larger of the load kVA and kW ÷ 0.8. A load of 50 kW at PF 0.85 is 58.8 kVA, but kW ÷ 0.8 = 62.5 kVA governs; with a 20% margin you would look for at least 75 kVA.
Motors take several times their running current when they start, and UPS or drive loads add harmonics, so large motors usually need a bigger set or a soft starter. Use the generator size calculator to add up appliances and starting loads, and the motor full-load current calculator for motor amps.
When to correct the power factor
A low power factor means more kVA and current for the same kW, which loads cables and transformers and can attract utility penalties. Adding capacitors supplies kVAR locally: 80 kW at 0.8 needs 33.7 kVAR to reach 0.95, cutting the kVA from 100 to 84.2. For capacitor µF, step sizes and the nameplate voltage, continue in the power factor correction calculator; for watts from volts and amps on DC or small loads, the watt calculator.
kVA to kW Converter FAQ
How do I convert kVA to kW?
Multiply by the power factor: kW = kVA × PF. At the common generator rating of 0.8, 62.5 kVA is 50 kW and 125 kVA is 100 kW. The kVA to kW converter above does this for any power factor.
What is the kVA to kW formula for 3 phase?
The same: kW = kVA × PF. Three-phase only changes the current: kVA = √3 × V × I ÷ 1,000 with the line-to-line voltage.
How many amps is 1 kVA?
On 230 V single-phase about 4.35 A; on 415 V three-phase about 1.39 A per line; on 480 V three-phase about 1.20 A.
Why are generators rated in kVA and not kW?
Because the alternator’s heating depends on current, whatever the power factor of the load. The kW the set can give depends on the load’s power factor, so makers quote kVA and assume 0.8.
How do I calculate kVAR?
kVAR = √(kVA² − kW²), or kW × tan φ. 100 kVA with 80 kW is 60 kVAR.
Can kW be larger than kVA?
No. kVA is always at least kW; they are equal only at a power factor of 1, for purely resistive loads such as heaters.