Motor Torque Converter

This tool converts torque values between five common engineering units: newton-meters (N·m), ounce-inches (oz·in), kilogram-centimeters (kg·cm), pound-feet (lb·ft), and millinewton-meters (mN·m). It also calculates mechanical power in watts using the formula P = τ × RPM × π/30, where τ is torque in N·m and RPM is rotational speed.

Engineers use it during motor selection, gearbox design, actuator sizing, and electromechanical system integration—especially when interpreting datasheets with mixed unit conventions or verifying torque/power specifications across international standards (e.g., converting a Japanese servo’s kg·cm rating to N·m for control loop tuning).

They map to standardized torque units: 1 = N·m, 2 = oz·in, 3 = kg·cm, 4 = lb·ft, and 5 = mN·m. This numeric input avoids dropdown complexity and supports quick keyboard entry—critical for field engineers or spreadsheet-based workflows.

RPM is optional for pure unit conversion—it’s only used to compute mechanical power. If you leave RPM blank or enter zero, the tool still performs torque conversion but omits the power result. The interface includes it by default because torque and speed are intrinsically linked in motor performance analysis.

Small DC motors: 1–100 mN·m; stepper motors: 0.1–5 N·m; industrial AC motors: 10–10,000+ N·m; electric vehicle traction motors: 200–800+ N·m. The calculator handles all ranges—just ensure input precision matches your application’s tolerance (e.g., avoid rounding sub-gram-force values).

Verify torque is entered in N·m *before* conversion—if you input 10 oz·in but set “From Unit” to 1 (N·m), results will be incorrect. Also confirm RPM is shaft speed—not electrical frequency—and that the π/30 constant assumes SI units (τ in N·m, RPM in revolutions per minute).

Conversions use internationally accepted constants: 1 N·m = 141.6119327 oz·in, 1 N·m = 10.1971621 kg·cm, and 1 N·m = 0.737562149 lb·ft. The tool rounds displayed results to 4 significant figures—sufficient for most design work but retain full precision for critical calculations.

Yes—the calculator treats torque as a scalar quantity and performs unit conversion regardless of context. However, note that static (holding) torque, peak (acceleration) torque, and continuous (thermal limit) torque must be selected appropriately from motor datasheets before entering values.

Yes—1 lb·ft = 12 lb·in. The tool uses lb·ft (pound-feet), the standard unit for larger motors and industrial drives. If your source specifies lb·in, divide by 12 before entering or convert manually using the tool’s oz·in output (since 1 lb·in = 16 oz·in).

The calculator outputs *mechanical output power* only. To estimate electrical input power, divide the result by motor efficiency (e.g., 85% → 0.85). Efficiency varies with load, speed, and temperature—always consult the motor’s efficiency map for accurate system-level power budgeting.