kVA ↔ kW ↔ BHP Converter
Apparent power, real power, and brake horsepower — three-way live converter.
How to use
Type a value in any of the three fields. The other two update using the current power factor and motor efficiency.
- Enter a value in kVA, kW, or BHP.
- Adjust the power factor (typically 0.8–1.0 for industrial motors).
- Adjust the motor efficiency (typically 0.85–0.95 for modern motors).
- Use for unit reference. Real motor sizing belongs to a licensed engineer or electrician.
Reviewed 3 June 2026 · methodology cited
About this converter
Electrical engineers and motor specialists work in three different power units. Apparent power, measured in kVA, is the product of voltage and current with no regard to phase. Real power, measured in kW, is the part of that apparent power that actually does useful work — the rest is reactive power that circulates without doing work. Brake horsepower (BHP) is the mechanical power delivered by a motor at the shaft, after the motor's own internal losses.
This converter handles all three units bidirectionally, using the standard formulas with adjustable power factor and motor efficiency. A motor nameplate gives you BHP (mechanical output), kW input is BHP ÷ efficiency, and kVA input is kW ÷ power factor. Reference values for power factor and efficiency live with the motor nameplate; default values here represent typical modern three-phase induction motors.
The conversion factors
Real power is apparent power times power factor: kW = kVA × PF. Apparent power is real power divided by power factor: kVA = kW ÷ PF. Brake horsepower from kW: BHP = kW × 1.341 × efficiency. Conversely kW input from BHP: kW = BHP ÷ (1.341 × efficiency).
The 1.341 converts kilowatts to mechanical horsepower exactly (1 hp = 0.7457 kW, so 1 kW = 1/0.7457 = 1.341 hp). Power factor of 1.0 means real power equals apparent power (purely resistive load). PF of 0.8 means real power is 80 percent of apparent — common for unloaded induction motors. Motor efficiency of 0.9 means 90 percent of input electrical power reaches the shaft.
A worked example: a 5 BHP motor at 0.9 efficiency consumes 5 ÷ (1.341 × 0.9) = 4.14 kW input. At 0.85 PF that draws 4.87 kVA. At 230 V three-phase, the line current is 4870 ÷ (230 × √3) = 12.2 A. Always check the actual nameplate for the motor on your bench.
Common motor sizes (NEMA)
| HP | kW | kVA @ 0.8 PF | A @ 230 V (3φ) |
|---|---|---|---|
| 1/2 | 0.37 | 0.46 | 1.5 |
| 1 | 0.75 | 0.94 | 3.0 |
| 2 | 1.49 | 1.86 | 6.0 |
| 3 | 2.24 | 2.80 | 9.0 |
| 5 | 3.73 | 4.66 | 15.0 |
| 7.5 | 5.59 | 6.99 | 22.0 |
| 10 | 7.46 | 9.33 | 30.0 |
| 15 | 11.2 | 14.0 | 44.0 |
| 20 | 14.9 | 18.6 | 58.0 |
| 25 | 18.6 | 23.3 | 72.0 |
| 30 | 22.4 | 28.0 | 88.0 |
| 50 | 37.3 | 46.6 | 146.0 |
| 100 | 74.6 | 93.3 | 292.0 |
Reference notes
Power factor varies with load. A modern three-phase induction motor at full load runs PF 0.85–0.92. At half load PF drops to 0.7–0.8; at no-load it can fall below 0.5. Capacitor banks correct PF closer to unity by supplying the reactive component locally rather than pulling it through the utility wires.
Motor efficiency varies less than PF, but it does vary. NEMA Premium efficient motors run 92–96 percent across most sizes; standard efficiency motors run 85–90 percent. Above 100 HP, premium efficiency is mandatory for new motors in many jurisdictions (US EPACT 2005, Canada CSA C390). Always check the actual nameplate efficiency rather than assuming a standard value, and remember: this is a reference converter, not a motor sizing tool.
Frequently asked questions
What is the difference between kVA and kW?
kVA is apparent power — voltage times current. kW is real power — the part of apparent power that does useful work. The ratio kW / kVA is the power factor. A purely resistive load (electric heater) has PF = 1, so kW = kVA. A motor or fluorescent lamp has PF < 1, so kW < kVA. Utilities bill for both because reactive current still flows through their wires.
What is "brake horsepower"?
Brake horsepower (BHP) is the mechanical power available at the motor shaft, measured by braking the shaft and reading the torque. It excludes the internal motor losses (iron, copper, windage). The electrical input power (kW) divided by efficiency equals BHP × 0.7457. Pump and compressor manufacturers quote BHP because that is what their machine actually delivers at the shaft.
Why does power factor matter?
Power factor determines how much current flows in the supply wires to deliver a given amount of real power. A 100 kW motor at PF 1.0 needs the wires to carry 100 kVA. The same motor at PF 0.7 needs 143 kVA, even though it does the same work. Lower PF means more current, more wire losses, and a larger transformer — utilities penalize industrial customers with PF below about 0.9.
What power factor should I use?
Read the motor nameplate. If unknown, default to 0.85 for a fully-loaded three-phase induction motor — slightly higher for premium-efficiency motors and slightly lower for single-phase. Resistive loads (heaters, incandescent lamps) are 1.0. Power-factor-corrected systems can be 0.95 or higher.
What motor efficiency should I use?
Read the nameplate. Defaults: 0.85 for older standard-efficiency motors, 0.92–0.96 for NEMA Premium. NEMA Premium efficiency tables published in NEMA MG 1 list minimum nominal efficiencies by horsepower and pole count. The actual operating efficiency varies with load — typically peaks at 75–100 percent load and drops at lighter loads.
Can I use this to size a motor?
No. This is a unit-conversion utility. Real motor sizing depends on load characteristics (constant torque, variable torque, fan, pump), starting requirements, duty cycle, ambient temperature, and the matching driven equipment. That is a job for the equipment manufacturer's engineering data and a licensed engineer.