Electric specs list kW; legacy equipment quotes hp. This guide walks through the kW to HP converter: shaft or electrical power in kilowatts and mechanical horsepower using the standard US conversion factor.
Benefits
- Core formula: HP = kW ÷ 0.7457 (mechanical hp).
- Bridges modern kW ratings with motor and pump nameplates in hp.
- Instant check before comparing VFD, genset, or compressor specs.
How it works
- Enter motor, generator, or load power in kilowatts (kW).
- Apply the mechanical horsepower constant: 1 hp ≈ 0.7457 kW.
- Read horsepower (hp)—the value most US motor plates and catalogs use.
FAQ
How do I convert kW to HP?
HP = kW ÷ 0.7457. Example: 7.5 kW → 7.5 ÷ 0.7457 ≈ 10.06 hp mechanical. Reverse: kW = hp × 0.7457. Use the same constant for three-phase and single-phase when the kW figure is already real power.
What is mechanical horsepower vs. metric hp?
Mechanical horsepower (US) = 0.7457 kW. Metric horsepower (PS, DIN) ≈ 0.7355 kW—common on European auto and small-engine labels. This calculator uses mechanical hp; check the nameplate region before quoting replacement motors.
When do I need kW to hp conversion?
Sizing replacements when the old motor is stamped in hp but the new inverter drive lists kW. Comparing pool pumps, air compressors, and farm equipment across catalogs that mix units. Verifying that a 10 hp nameplate motor matches a 7.5 kW VFD rating line.
Technical specifications
- Mechanical HP = kW ÷ 0.7457.
- kW = HP × 0.7457 (reverse).
- 1 mechanical hp = 745.7 W = 0.7457 kW.
- Related: kw-to-hp, kva-to-kw, amps-to-watts, inverter-sizing.
kW is electrical; hp is how motors are sold
Variable-frequency drives, solar inverters, and utility bills speak kilowatts. Centrifugal pumps, shop air compressors, and NEMA motor frames still advertise mechanical horsepower. The conversion is fixed: divide kW by 0.7457 for US mechanical hp. A 5.6 kW continuous rating is a 7.5 hp class motor—not 5.6 hp. Mixing units without converting causes undersized breakers or disappointed torque expectations.
Mechanical hp is the US standard for industrial equipment
IEEE and NEMA motor tables assume mechanical horsepower. Metric PS appears on imported small engines and some EV marketing abroad. When a datasheet says 10 hp and you are matching a 7.5 kW VFD, you are aligned. When it says 10 PS, the kW equivalent is slightly lower. Document which hp definition you used on the BOM so installers do not swap incompatible units.
From hp back to electrical planning
After hp is confirmed, continue in kW for wire sizing and inverter headroom—amps follow from kW and voltage, not hp alone. Pair this converter with kVA to kW when generator apparent power is involved, or Amps to Watts when you need branch-circuit load from a hp-rated motor at a known efficiency and power factor.