Motor HP Torque Speed Calculator

⚡ Motor HP / Torque / Speed Calculator

Convert between horsepower, torque, RPM, kW, and N·m

Common Motor Presets

Results

Conversion Formulas

HP = Torque (lb·ft) × RPM / 5252

Torque (lb·ft) = HP × 5252 / RPM

kW = HP × 0.7457  |  N·m = lb·ft × 1.35582

Input power (kW) = Output kW / Efficiency  |  Full-load current (A) ≈ HP × 746 / (V × PF × Eff × √3) for 3-phase

📝 Worked Example

A conveyor drive requires 30 lb·ft of load torque at 1,750 RPM. Size a standard NEMA motor at 93% efficiency with a 1.15 service factor.

InputValue
ModeMotor Sizing
Load Torque Required30 lb·ft
Speed (RPM)1,750 RPM
Efficiency (η)93%
Service Factor1.15 (Standard NEMA)

Step 1 — Output HP from load: HPout = T × RPM / 5252 = 30 × 1750 / 5252 = 9.99 HP.

Step 2 — Account for efficiency: HPshaft = 9.99 / 0.93 = 10.74 HP required at motor shaft.

Step 3 — Apply service factor: Min HPmotor = 10.74 × 1.15 = 12.35 HP.

Step 4 — Select standard NEMA frame: Next standard size above 12.35 HP = 15 HP.

Step 5 — Convert to SI: 15 HP × 0.7457 = 11.19 kW. Torque in N·m = 30 × 1.35582 = 40.67 N·m.

Expected Results: Required HP ≈ 10.74  |  Min HP (with SF 1.15) ≈ 12.35  |  Recommended Motor: 15 HP NEMA  |  Torque ≈ 30.00 lb·ft / 40.67 N·m  |  Output: 11.19 kW

Switch to “Motor Sizing” tab, enter Load Torque = 30 lb·ft and RPM = 1750 to verify.