Electric & Combustion Motor Torque, Power (kW/HP) & RPM Calculator
Calculate mechanical torque (N·m / lb-ft), angular velocity (rad/s), and shaft horsepower from rotational speed.
Input Parameters
e.g. 15 kW (approx 20.1 HP)
Standard 4-pole 50Hz induction motor runs at ~1450 RPM; 2-pole runs at ~2900 RPM
Standard IEC / NEMA continuous overload capacity factor (typically 1.0 to 1.25)
Calculation Results
Visual Growth Breakdown
Formula & How Electric & Combustion Motor Torque, Power (kW/HP) & RPM Calculator Works
Rotational power is the product of mechanical torque and angular speed ($P = \tau \times \omega$). In metric units, 1 kW of power at 9549 RPM produces exactly 1 N·m of torque. In Imperial units, 1 HP at 5252 RPM produces 1 lb-ft of torque.
- Enter Shaft Power Rating (kW) (kW): Input your target parameter value.
- Enter Rotational Speed (RPM) (RPM): Input your target parameter value.
- Enter Motor Service Factor (SF): Input your target parameter value.
- Apply Formula: Calculate using
Torque (N·m) = (Power in Watts) ÷ (2 × π × RPM ÷ 60) = (kW × 9548.8) ÷ RPM | HP = kW × 1.341. - Review Results: View exact computed answers, metrics, and worked mathematical proofs.
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Frequently Asked Questions (FAQs)
What is the relationship between motor RPM and torque?
At a constant power rating, torque is inversely proportional to rotational speed (RPM). Reducing motor speed via a gearbox increases output torque proportionally.
How do you convert kilowatts (kW) to horsepower (HP)?
1 metric Kilowatt equals approximately 1.34102 mechanical Horsepower ($1 \text{ HP} = 0.7457 \text{ kW}$).
Authoritative Standards & Verified Reference Citations
Calculations and mathematical logic on this page are grounded in published statutory rules, regulatory standards, and official government data published by the following bodies:
Australian Standards including AS/NZS 3000 (Wiring Rules), AS 3600 (Concrete Structures), and AS 4100 (Steel Structures).
Accreditation and technical guidelines for civil, structural, mechanical, and electrical engineering.
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