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Convert real power in kilowatts (kW) to apparent power in kilovolt-amperes (kVA). Essential for sizing generators, transformers, and electrical equipment.
Typical values: Motors 0.8, Mixed loads 0.85, Resistive loads 1.0
kVA = kW ÷ PF
Kilovolt-amps equals kilowatts divided by power factor
kVAR = √(kVA² - kW²)
Reactive power from the power triangle
| kW | kVA @ PF 0.8 | kVA @ PF 0.85 | kVA @ PF 0.9 | kVA @ PF 0.95 | kVA @ PF 1.0 |
|---|---|---|---|---|---|
| 10 kW | 12.50 kVA | 11.76 kVA | 11.11 kVA | 10.53 kVA | 10.00 kVA |
| 25 kW | 31.25 kVA | 29.41 kVA | 27.78 kVA | 26.32 kVA | 25.00 kVA |
| 50 kW | 62.50 kVA | 58.82 kVA | 55.56 kVA | 52.63 kVA | 50.00 kVA |
| 75 kW | 93.75 kVA | 88.24 kVA | 83.33 kVA | 78.95 kVA | 75.00 kVA |
| 100 kW | 125.00 kVA | 117.65 kVA | 111.11 kVA | 105.26 kVA | 100.00 kVA |
| 150 kW | 187.50 kVA | 176.47 kVA | 166.67 kVA | 157.89 kVA | 150.00 kVA |
| 200 kW | 250.00 kVA | 235.29 kVA | 222.22 kVA | 210.53 kVA | 200.00 kVA |
| 500 kW | 625.00 kVA | 588.24 kVA | 555.56 kVA | 526.32 kVA | 500.00 kVA |
Converting kilowatts (kW) to kilovolt-amperes (kVA) bridges the gap between real power and apparent power in AC electrical systems. Real power (kW) represents the actual energy consumed by a load to perform useful work, while apparent power (kVA) accounts for the total power the source must deliver, including reactive power that sustains electromagnetic fields in motors, transformers, and other inductive equipment. The conversion requires knowing the power factor (PF), which is the ratio of real to apparent power. This calculation is critical when sizing generators, transformers, and switchgear, because these components must be rated to handle the full apparent power flowing through them. Utilities and the NEC (National Electrical Code) base infrastructure sizing on kVA, making this conversion indispensable for electrical engineers, facility managers, and anyone specifying power distribution equipment per IEEE C57 and NEC Article 220 standards.
Find the total kW demand by summing the rated power of all connected loads. For motors, use the nameplate kW or HP rating (1 HP = 0.746 kW). For lighting and heating, use the listed wattage divided by 1,000.
Measure PF with a power quality analyzer or use typical values: 0.80 for motor-heavy loads, 0.85 for mixed commercial, 0.90–0.95 for modern electronic loads, and 1.0 for purely resistive loads like heaters.
Divide the kW value by the power factor. For example, 100 kW ÷ 0.85 PF = 117.65 kVA. This tells you the apparent power the electrical infrastructure must support.
Round up to the nearest standard kVA rating. Common transformer sizes include 15, 25, 37.5, 50, 75, 100, 150, 200, 300, and 500 kVA per ANSI C57.12 standards. Add 20–25% margin for future growth.
Generators are rated in kVA because alternator windings must handle full apparent current. Undersizing by using kW instead of kVA leads to overheating and voltage instability under load.
Commercial utilities charge demand fees based on kVA. Improving power factor from 0.8 to 0.95 reduces kVA demand by 16%, directly lowering monthly demand charges and penalty fees.
Cables, busbars, and switchgear are sized for apparent power (kVA). Accurate kW-to-kVA conversion ensures conductors and protective devices are rated for actual current flow per NEC Article 220.
| Transformer kVA | kW @ PF 0.80 | kW @ PF 0.85 | kW @ PF 0.90 | kW @ PF 1.0 |
|---|---|---|---|---|
| 15 kVA | 12 kW | 12.75 kW | 13.5 kW | 15 kW |
| 25 kVA | 20 kW | 21.25 kW | 22.5 kW | 25 kW |
| 50 kVA | 40 kW | 42.5 kW | 45 kW | 50 kW |
| 75 kVA | 60 kW | 63.75 kW | 67.5 kW | 75 kW |
| 100 kVA | 80 kW | 85 kW | 90 kW | 100 kW |
| 200 kVA | 160 kW | 170 kW | 180 kW | 200 kW |
| 500 kVA | 400 kW | 425 kW | 450 kW | 500 kW |
kVA measures apparent power while kW measures real power. Since power factor ranges from 0 to 1, dividing kW by PF always produces an equal or larger number. The difference represents reactive power (kVAR) consumed by inductive and capacitive loads. Only when PF equals exactly 1.0 (purely resistive loads like heaters) are kW and kVA equal.
Use 0.80 as a conservative default for mixed commercial and industrial loads. Motor-heavy facilities typically run 0.75–0.85. Modern electronic loads with power factor correction achieve 0.90–0.99. Purely resistive loads (heaters, incandescent lights) are 1.0. Using a lower PF provides a larger safety margin for equipment sizing.
Yes. Install power factor correction capacitors at the main switchboard or individual motor starters. Improving PF from 0.80 to 0.95 for a 100 kW load reduces kVA from 125 to 105.3, freeing transformer capacity and reducing utility demand charges. Many utilities penalize customers with PF below 0.85–0.90.
Generator alternator windings and cooling systems are designed to handle current, not power. Since current depends on apparent power (kVA), the kVA rating tells you the maximum current the generator can safely deliver at rated voltage, regardless of load power factor. The engine driving the alternator has a separate kW rating for fuel consumption.
Many commercial utility tariffs include a demand charge based on peak kVA. A low power factor increases your kVA demand relative to the kW you actually use, resulting in higher demand charges. Some utilities explicitly charge a power factor penalty when PF drops below 0.85–0.90. Correcting PF can save 10–30% on demand charges.