Convert apparent power in kVA to mechanical horsepower (HP). Enter kVA, power factor, and motor efficiency to get accurate HP output for motor and generator planning.
✓ Verified: NEMA MG 1 — Motors and Generators | IEC 60034 — Rotating Electrical Machines — April 2026
kVA
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Apparent power in kilovolt-amperes
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AC motor typical: 0.80-0.95. Use 0.85 if unknown.
%
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NEMA motors: 85-95%. Use 90% if unknown.
Convert apparent power in kVA to mechanical horsepower (HP). Enter kVA, power factor, and motor efficiency to get accurate HP output for motor and generator planning.
Horsepower (HP)
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⚠️ Disclaimer: These calculations are for planning purposes only. Always verify against motor nameplate data and consult a licensed electrical engineer for actual motor and generator system design.
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Sources & Methodology
✓ Formulas verified against authoritative sources listed below.
IEC international standard for motor efficiency classes and output power definitions
Methodology: kW input = kVA x PF. kW output (shaft) = kW input x Efficiency. HP = kW output / 0.7457. 1 HP = 745.7 W (mechanical, IEC standard). Efficiency accounts for motor losses: heat, friction, windage. Typical NEMA premium efficiency: 92-95%. Standard: 85-90%.
⏱ Last reviewed: April 2026
How to Convert kVA to Horsepower
Converting kVA to horsepower requires two steps: first converting apparent power (kVA) to real power (kW) using the power factor, then converting real power input to mechanical shaft output using motor efficiency. The result is the mechanical horsepower the motor delivers at the shaft. This calculation is used when sizing motors from generator or transformer kVA ratings.
Step 1: kVA to kW Using Power Factor
Real power (kW) = kVA x Power Factor. Power factor represents the ratio of real power to apparent power. A 10 kVA source at PF 0.85 delivers 8.5 kW of real power to the motor. The remaining 1.5 kW equivalent is reactive power (kVAR) that does no useful work but must still be supplied by the source.
Step 2: kW Input to HP Output Using Efficiency
Motor shaft output (kW) = kW input x Efficiency. HP = kW output / 0.7457. A motor drawing 8.5 kW at 90% efficiency delivers 8.5 x 0.90 = 7.65 kW at the shaft = 7.65 / 0.7457 = 10.26 HP. The efficiency loss (10%) becomes heat in the motor windings and mechanical losses.
Why kVA Ratings Matter for Motor Selection
When selecting a motor from a generator or UPS spec sheet, the kVA rating tells you the maximum apparent power available. The motor must be sized so its kVA demand (HP x 0.7457 / Eff / PF) does not exceed the source kVA. Oversizing the motor relative to the source causes voltage sag and protection trips.
NEMA Efficiency Ratings
NEMA Premium motors (EPAct 2007): efficiency typically 92-96% at full load. Standard efficiency (pre-EPAct): 85-90%. IE3 (IEC equivalent of NEMA Premium): widely used in international markets. At partial load (50-75%), motor efficiency drops — account for this when calculating HP at typical operating conditions.
kW input = kVA x PF | kW output = kW input x Efficiency | HP = kW output / 0.7457
1 HP = 745.7 W = 0.7457 kW (mechanical, IEC). Power factor typical range: 0.80-0.95. Efficiency typical range: 0.85-0.95. Example: 15 kVA, PF 0.85, Eff 90%: kW in = 12.75, kW out = 11.475, HP = 15.39.
kVA to HP Conversion Table (PF 0.85, Eff 90%)
kVA
kW Input
kW Output
Horsepower (HP)
5 kVA
4.25 kW
3.825 kW
5.13 HP
10 kVA
8.50 kW
7.650 kW
10.26 HP
15 kVA
12.75 kW
11.475 kW
15.39 HP
20 kVA
17.00 kW
15.300 kW
20.52 HP
25 kVA
21.25 kW
19.125 kW
25.64 HP
50 kVA
42.50 kW
38.250 kW
51.29 HP
75 kVA
63.75 kW
57.375 kW
76.94 HP
100 kVA
85.00 kW
76.500 kW
102.6 HP
⚡ Generator Sizing Tip: To find kVA needed for a known HP motor: kVA = (HP x 0.7457) / (Eff x PF). For a 50 HP motor at 90% efficiency and 0.85 PF: kVA = (50 x 0.7457) / (0.90 x 0.85) = 37.285 / 0.765 = 48.74 kVA. Always add 25% headroom for motor starting surge.
Frequently Asked Questions
kW input = kVA x Power Factor. kW output = kW input x Efficiency. HP = kW output / 0.7457. Example: 10 kVA, PF 0.85, 90% efficiency: kW in = 8.5, kW out = 7.65, HP = 10.26.
At PF 0.85 and 90% efficiency: HP = (10 x 0.85 x 0.90) / 0.7457 = 7.65 / 0.7457 = 10.26 HP. The exact result depends on power factor and efficiency.
HP = (kVA x PF x Eff) / 0.7457. Where PF = power factor (0.80-0.95) and Eff = motor efficiency (0.85-0.95). 1 HP = 0.7457 kW (mechanical).
kVA = (HP x 0.7457) / (Eff x PF). For 1 HP at 90% efficiency and 0.85 PF: kVA = 0.7457 / (0.90 x 0.85) = 0.7457 / 0.765 = 0.975 kVA. Approximately 1 kVA per 1 HP.
1 mechanical horsepower = 745.7 watts = 0.7457 kW (IEC standard). 1 metric horsepower = 735.499 W. Most electrical calculations use the mechanical HP = 0.7457 kW definition.
No. kVA is apparent power from the electrical supply — it includes both real power (kW) and reactive power (kVAR). Motor efficiency is a separate factor that reduces the shaft output below the real power input. To get HP: convert kVA to kW (via PF), then apply efficiency, then convert to HP.
At PF 0.85 and motor efficiency 90%: HP = (25 x 0.85 x 0.90) / 0.7457 = 19.125 / 0.7457 = 25.6 HP maximum. In practice, derate for motor starting surges and other connected loads.
NEMA Premium motors meet efficiency standards set by NEMA MG 1 Table 12-12. For a 10 HP, 4-pole motor, NEMA Premium requires minimum 91.7% efficiency at full load. Higher efficiency means more HP output per kVA drawn from the supply.
Higher power factor = more real power (kW) from the same kVA = more HP. At PF 0.80: 10 kVA = 8.0 kW. At PF 0.95: 10 kVA = 9.5 kW. The difference (1.5 kW) at 90% efficiency = about 1.8 HP more output from the same kVA source.
kVA measures apparent electrical power from the source. HP measures mechanical shaft output from the motor. They are related by power factor (kVA to kW) and motor efficiency (kW to HP). 1 HP always requires more than 1 kW input because of efficiency losses.