Enter values to see results
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N·m
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lb·ft
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kg·m
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oz·in
Enter values to see results
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N·m
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lb·ft
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kg·m
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oz·in
Torque is one of the most important parameters in electrical machine design and motor selection. It represents the rotational force that an electric motor, generator, servo drive, or actuator can produce, and is defined as force multiplied by the perpendicular distance from the axis of rotation. In electrical engineering, torque specifications appear in motor datasheets, variable frequency drive (VFD) settings, servo motor configurations, and rotating machine test reports — often in different unit systems depending on the region and industry standard used.
The Torque Converter for Electrical Applications enables instant, accurate conversion between Newton-meters (N·m), pound-feet (lb·ft), pound-inches (lb·in), kilogram-centimeters (kg·cm), kilogram-meters (kg·m), millinewton-meters (mN·m), and ounce-inches (oz·in). Whether you are sizing a three-phase induction motor for an industrial drive, specifying a servo actuator for a robotic arm, or reading a North American motor datasheet in a metric-standard country, this tool bridges the unit gap instantly.
Electric motors are rated by both power and torque. While power (in watts or horsepower) is the more commonly cited figure, torque is what actually accelerates loads, overcomes friction, and maintains speed under varying load conditions. The relationship P = τ × ω (power equals torque times angular velocity) links these quantities — understanding both is essential for motor sizing and drive configuration. VFDs display torque feedback in N·m or as a percentage of rated torque; converting to lb·ft is necessary when consulting North American mechanical specifications or legacy equipment documentation.
In servo and stepper motor applications, torque specifications are often given in mN·m (millinewton-meters) or oz·in (ounce-inches) for small precision motors. A stepper motor rated at 4,400 mN·m equals 4.4 N·m = approximately 3.25 lb·ft = 63.4 oz·in. Choosing the wrong unit for a torque setpoint in a motion controller can result in dramatically wrong force output — potentially damaging equipment or creating unsafe conditions.
Industrial bolting and fastening applications in electrical switchgear assembly require precise torque values. Busbar bolts, terminal connections, and transformer tap changer contacts all have torque specifications that must be met during installation and maintenance. IEC standards typically specify torque in N·m, while ANSI/NEMA standards may use lb·ft or lb·in. Field technicians carrying North American torque wrenches to service European-standard equipment need reliable conversion to ensure proper joint integrity.
Generator coupling and direct-drive wind turbine generators involve very high torque values, often in the hundreds of thousands of N·m range. Converting these values to lb·ft helps when integrating with North American drivetrain components or when comparing with imperial-rated couplings and gearboxes. At the opposite extreme, micro-motors in precision instruments, MEMS devices, and wearable electronics may be rated in µN·m, requiring conversion to oz·in or mN·m for practical comparison.
This converter uses Newton-meters as the universal base unit. All source units are first converted to N·m using exact or NIST-standardized conversion factors, then converted to the target unit. The results panel simultaneously shows the value in N·m, lb·ft, kg·m, and oz·in, providing comprehensive cross-reference in a single calculation. Conversion factors used: 1 lb·ft = 1.3558179 N·m, 1 lb·in = 0.1129848 N·m, 1 kg·cm = 0.0980665 N·m, 1 kg·m = 9.80665 N·m, 1 mN·m = 0.001 N·m, 1 oz·in = 0.0070616 N·m.
The calculator converts all torque units through Newton-meters as the common base. The input value is multiplied by the conversion factor to N·m, then the N·m value is multiplied by the inverse factor to reach the target unit. For example, converting 10 lb·ft to N·m: 10 × 1.3558179 = 13.558 N·m. Converting 13.558 N·m to kg·m: 13.558 × 0.1019716 = 1.382 kg·m. The output panel shows the N·m equivalent, lb·ft, kg·m, and oz·in values simultaneously for complete reference. All conversions use double-precision floating-point arithmetic with NIST-standardized factors.
Fractional horsepower motors (under 1 hp) typically produce 1–7 N·m (0.74–5.16 lb·ft) of rated torque. Standard industrial motors (1–100 hp) range from 5–500 N·m (3.7–369 lb·ft). Servo motors for CNC and robotics are commonly rated 0.1–50 N·m. Stepper motors range from 100 mN·m to 10 N·m. Large traction motors (EV, locomotive) can exceed 10,000 N·m. For terminal torque specifications: M3 screws typically require 0.5–0.8 N·m, M6 terminals 4–6 N·m, M10 bus-bar bolts 25–35 N·m.
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A 85 lb·ft rated motor torque converts to 115.24 N·m. This is typical for a 15–20 kW (20–27 hp) industrial induction motor at rated speed.
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A servo motor rated at 3,500 mN·m (3.5 N·m) produces approximately 495.6 oz·in of torque, which is a common rating for NEMA 23 frame servo and stepper motors used in CNC machinery.
Torque determines whether a motor can start and accelerate a load, maintain speed under varying load conditions, and handle peak demand without stalling. Insufficient torque causes motor stall, overheating, and potential drive fault trips. The required torque must be calculated from the mechanical load (inertia, friction, gravity components) and compared against the motor's torque-speed curve across the full operating range.
Rated torque (also called full-load torque) is the continuous torque the motor delivers at its rated speed and power. Starting torque (locked rotor torque) is the torque produced at zero speed. Induction motors typically have starting torque of 150–200% of rated torque. Breakaway torque is the initial torque needed to overcome static friction in the load. All three values may appear in different units depending on the motor's market of origin.
The relationship is P = τ × ω, where P is power in watts, τ is torque in N·m, and ω is angular velocity in rad/s. Rearranging: τ = P / ω. For RPM-based calculations: τ (N·m) = (P in watts × 60) / (2π × RPM) = 9549 × P(kW) / RPM. For horsepower: τ (lb·ft) = 5252 × HP / RPM. This is the fundamental formula used in all motor sizing calculations.
Servo motor datasheets vary by manufacturer and region. European and Japanese manufacturers typically use N·m for larger motors and mN·m for smaller precision servos. North American datasheets often use oz·in for small motors and lb·ft or lb·in for larger units. Motion control software (Beckhoff TwinCAT, Siemens TIA Portal, Allen-Bradley Studio 5000) may use any of these units in their configuration parameters.
Continuous torque is the torque a motor can sustain indefinitely without exceeding thermal limits. Peak torque is the maximum torque available for short durations (typically 1–10 seconds) during acceleration or overload events. Servo motors may offer peak torque 2–3x continuous rating. For proper sizing, the duty cycle must be analyzed — intermittent high-torque demands are acceptable as long as the RMS torque over the cycle does not exceed the continuous rating.
Undertorqued electrical connections create high-resistance joints that heat up, oxidize, and ultimately fail — causing fires, equipment damage, or downtime. Overtorqued connections can crack insulators, strip threads, or damage bus bar components. IEC 60999 and NEMA standards specify exact torque values for terminal connections. In high-current applications (bus bars, transformer taps, switchgear contacts), even small deviations from specified torque can significantly affect contact resistance and long-term reliability.
1 N·m = 0.7375621 lb·ft (exactly: 1/(0.3048 × 4.4482216)). Conversely, 1 lb·ft = 1.3558179 N·m. These factors are derived from the exact definitions: 1 foot = 0.3048 m and 1 pound-force = 4.4482216 N. For quick mental approximation: N·m × 0.738 ≈ lb·ft, or lb·ft × 1.356 ≈ N·m.
In DC motors: τ = Kt × I, where Kt is the torque constant (N·m/A) and I is armature current. The torque constant Kt equals the back-EMF constant Ke numerically (in SI units). In AC induction motors, the relationship is more complex but at constant flux: torque is proportional to rotor current (and thus to slip). In permanent magnet synchronous motors (PMSM), torque = 1.5 × p × λ × iq, where p is pole pairs, λ is flux linkage, and iq is the q-axis current component.
Torque specifications for electrical enclosure assembly depend on fastener size and material. Typical values: M3 (0.5–0.8 N·m / 4.4–7.1 lb·in), M4 (1.2–1.8 N·m / 10.6–15.9 lb·in), M5 (2.5–3.5 N·m / 22–31 lb·in), M6 (4–6 N·m / 35–53 lb·in), M8 (10–14 N·m / 7.4–10.3 lb·ft), M10 (20–28 N·m / 14.8–20.6 lb·ft). Always consult the equipment manufacturer's specifications as material and coating affect required torque values.
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