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Convert apparent power in kilovolt-amperes (kVA) to real power in kilowatts (kW). Calculate actual power consumption using power factor.
Typical values: Motors 0.8, Resistive loads 1.0, Mixed loads 0.85
kW = kVA × PF
Kilowatts equals kilovolt-amps times power factor
kVAR = kVA × √(1 - PF²)
Calculates reactive (wasted) power
The relationship between kVA, kW, and kVAR:
kVA² = kW² + kVAR²
| kVA | kW @ PF 0.8 | kW @ PF 0.85 | kW @ PF 0.9 | kW @ PF 0.95 | kW @ PF 1.0 |
|---|---|---|---|---|---|
| 10 kVA | 8 kW | 8.5 kW | 9 kW | 9.5 kW | 10 kW |
| 25 kVA | 20 kW | 21.25 kW | 22.5 kW | 23.75 kW | 25 kW |
| 50 kVA | 40 kW | 42.5 kW | 45 kW | 47.5 kW | 50 kW |
| 75 kVA | 60 kW | 63.75 kW | 67.5 kW | 71.25 kW | 75 kW |
| 100 kVA | 80 kW | 85 kW | 90 kW | 95 kW | 100 kW |
| 150 kVA | 120 kW | 127.5 kW | 135 kW | 142.5 kW | 150 kW |
| 200 kVA | 160 kW | 170 kW | 180 kW | 190 kW | 200 kW |
| 500 kVA | 400 kW | 425 kW | 450 kW | 475 kW | 500 kW |
| 1000 kVA | 800 kW | 850 kW | 900 kW | 950 kW | 1000 kW |
| Load Type | Power Factor | Notes |
|---|---|---|
| Resistive Heaters | 1.0 | Perfect power factor, all power is real power |
| Incandescent Lighting | 1.0 | Purely resistive load |
| LED Lighting | 0.9-0.95 | With power factor correction |
| Fluorescent Lighting | 0.5-0.9 | Varies with ballast type |
| AC Motors | 0.75-0.85 | Induction motors at full load |
| Computer Equipment | 0.65-0.8 | Switched mode power supplies |
| Welders | 0.5-0.7 | Arc welding equipment |
kVA to kW conversion determines how much real, usable power is available from a given apparent power supply. Kilovolt-amperes (kVA) represent apparent power — the total electrical power flowing through a circuit including both the productive component and the reactive component that sustains magnetic fields in motors and transformers. Kilowatts (kW) represent real power — the portion that actually performs useful work like turning a motor shaft, generating heat, or powering electronics. The bridge between these two measurements is the power factor, a dimensionless number between 0 and 1 that quantifies the efficiency of power delivery. Understanding this conversion is critical for accurately sizing electrical systems and interpreting equipment specifications across different manufacturers and standards.
Locate the kVA rating on the transformer, generator, or UPS nameplate. This is the maximum apparent power capacity. For example, a standard commercial transformer might be rated at 150 kVA.
Measure the power factor with a power analyzer, or use typical values: 0.80 for motor-heavy facilities, 0.85-0.90 for mixed commercial loads, 0.95-1.0 for resistive loads. Many modern power meters display power factor in real time.
Multiply kVA by the power factor: kW = kVA × PF. For the 150 kVA transformer at 0.85 PF: kW = 150 × 0.85 = 127.5 kW of real power available.
To find the reactive power: kVAR = kVA × √(1 - PF²). For 150 kVA at 0.85 PF: kVAR = 150 × √(1 - 0.7225) = 150 × 0.527 = 79 kVAR. This tells you how much reactive compensation is needed for unity power factor.
Electrical loads are often specified in kW (real power consumed) but must be supplied from equipment rated in kVA. Without proper conversion, you cannot accurately determine whether a transformer or generator has enough capacity for the connected loads.
Commercial electricity bills often include both kW demand charges and kVA demand charges. Understanding the relationship helps facility managers identify power factor issues that inflate costs, sometimes by 10-20% or more.
A low power factor means more kVA (and more current) is needed to deliver the same kW. This increases copper losses in conductors, reduces transformer capacity, and generates unnecessary heat throughout the electrical system.
| kVA | Power Factor | kW (Real) | kVAR (Reactive) |
|---|---|---|---|
| 100 | 1.00 | 100.0 | 0.0 |
| 100 | 0.95 | 95.0 | 31.2 |
| 100 | 0.90 | 90.0 | 43.6 |
| 100 | 0.85 | 85.0 | 52.7 |
| 100 | 0.80 | 80.0 | 60.0 |
| 100 | 0.75 | 75.0 | 66.1 |
| 100 | 0.70 | 70.0 | 71.4 |
| 100 | 0.65 | 65.0 | 76.0 |
| 100 | 0.60 | 60.0 | 80.0 |
Based on 100 kVA. Scale proportionally for other kVA ratings. kVAR = kVA × √(1 - PF²).
The power triangle is a right triangle that visually represents the relationship between the three types of electrical power. kVA (apparent power) forms the hypotenuse, kW (real power) forms the adjacent side, and kVAR (reactive power) forms the opposite side. The angle between kVA and kW is called the phase angle, and its cosine equals the power factor. This geometric relationship means kVA² = kW² + kVAR².
Most residential customers are billed only on kWh (real energy consumed). Commercial and industrial customers typically face demand charges based on peak kW or kVA demand, plus energy charges per kWh. Many utilities impose power factor penalties when PF drops below 0.85-0.90, effectively charging for the excess kVA relative to kW.
Yes, absolutely. Understanding the kVA to kW relationship reveals how much reactive power your facility wastes. By improving power factor with capacitor banks or synchronous motors, you reduce kVA demand, lower current draw, decrease I²R losses in conductors, and avoid utility power factor penalties. Many facilities see 5-15% reductions in electricity costs after power factor correction.
Using too high a power factor overestimates the kW output available from a kVA source, leading to undersized equipment that overloads. Using too low a power factor underestimates kW, resulting in oversized equipment that wastes capital. Always use measured power factor values from a power analyzer when available, rather than general estimates.
No. The fundamental formula kW = kVA × PF applies regardless of whether the system is single-phase or three-phase. The number of phases affects the relationship between kVA, voltage, and current, but the conversion from apparent power (kVA) to real power (kW) through the power factor remains identical in all AC systems.