RFrftools.io
Convert

Torque Unit Converter (N·m/lb·ft/oz·in)

Convert torque between Newton-metres, pound-feet, pound-inches, oz·in, kg·cm, kg·m, and dyne·cm.

Loading calculator...

Formula

1 N·m = 0.7376 lb·ft = 141.6 oz·in

How It Works

Torque is a rotational force measured as force × distance. The SI unit is Newton-metre (N·m). Imperial units include pound-foot (lb·ft) and pound-inch (lb·in). Motor datasheets, especially for hobby servos and small motors, commonly use oz·in (ounce-inch) and kg·cm (kilogram-centimetre). The relationship is: 1 N·m = 0.7376 lb·ft = 8.851 lb·in = 141.6 oz·in = 10.197 kg·cm.

Worked Example

A servo motor rated at 60 oz·in of torque: 60 oz·in ÷ 141.612 = 0.424 N·m = 0.312 lb·ft = 3.74 lb·in = 4.32 kg·cm. A car engine producing 250 N·m: 250 N·m = 184.4 lb·ft = 2213 lb·in = 35,403 oz·in = 2549 kg·cm.

Practical Tips

  • ✓Hobby servo motors are typically rated in kg·cm or oz·in at 4.8 V or 6 V — torque varies with supply voltage, so check the rating at your operating voltage.
  • ✓Robot arm joint torque requirements grow with arm length and payload mass — double the arm length and you need double the torque for the same load.
  • ✓When comparing motors across manufacturers, convert everything to N·m first; it eliminates confusion from mixed imperial and metric specifications.

Common Mistakes

  • ✗Confusing kg·cm (kilogram-centimetre, often called kgf·cm) with kg·m — they differ by 100×. A servo rated at 5 kg·cm produces only 0.05 kg·m.
  • ✗lb·ft and lb·in are frequently confused in US datasheets — lb·ft is 12× larger than lb·in. Always check which unit a torque rating uses.
  • ✗Forgetting that torque units imply a force unit: oz·in uses ounce-force (ozf), not mass. Technically oz·in = ozf·in to be precise about the gravitational context.

Frequently Asked Questions

N·m (Newton-metre) is torque or energy (force × distance). N/m (Newton per metre) is spring stiffness (force/distance). They are completely different physical quantities despite similar notation.
Oz·in became standard in the RC hobby industry decades ago when US manufacturers dominated. A typical micro servo produces 20–40 oz·in (0.14–0.28 N·m), while standard servos are 60–100 oz·in (0.42–0.71 N·m).
Torque = mass × gravity × lever arm length. For a 0.5 kg load at 0.2 m from the joint: T = 0.5 × 9.81 × 0.2 = 0.981 N·m. Add a safety factor of 2–3× for acceleration and dynamic loads.
Stall torque is the maximum torque a motor produces when its shaft is prevented from rotating (zero speed). Operating near stall torque generates maximum heat; continuous operation should be at 50–70% of stall torque.

Related Calculators

Motor

Torque Converter

Convert torque between Newton-metres, pound-feet, pound-inches, oz·in, kg·cm and dyne·cm — covers all motor datasheet units.

Motor

Gear Ratio

Calculate gear ratio, output speed, torque multiplication, and power transmission efficiency for gear trains.

Motor

DC Motor

Calculate DC motor speed, torque, power, and efficiency from electrical parameters

Convert

Frequency ↔ Wavelength

Convert frequency to wavelength in any medium. Calculates full, half, and quarter wavelengths for antenna design, transmission line, and RF system planning.

Convert

dBm ↔ Watts

Convert RF power between dBm, Watts, milliwatts, dBW, dBμV, and RMS volts into 50Ω. Essential for link budgets, amplifier analysis, and RF system design.

Convert

Temperature Converter

Convert temperature between Celsius, Fahrenheit, Kelvin, Rankine, and Réaumur scales. Useful for thermal analysis, datasheet comparison, and engineering calculations.