Torque Converter (Nm, ft-lb, kgf-cm)

About Torque Converter (Nm, ft-lb, kgf-cm)

The Torque Converter instantly converts torque values between every common unit — Newton-meter (N·m), foot-pound (ft·lb), inch-pound (in·lb), kilogram-force centimeter (kgf·cm), kilogram-force meter (kgf·m), dyne-centimeter (dyn·cm), and ounce-inch/foot. Unlike single-pair converters, this tool shows all eight units at once, includes a visual force × radius diagram, and compares your input to real-world references such as a car wheel lug nut, bike pedal, or spark plug — so you can sanity-check your value at a glance.

What is Torque?

Torque (also called moment of force) measures the rotational effort produced when a force is applied at a distance from a pivot. The defining equation is:

τ = F × r

Where τ (tau) is torque, F is the applied force, and r is the perpendicular distance (the lever arm) from the pivot to where the force acts. Doubling either the force or the lever arm doubles the torque — that's why a longer wrench loosens stubborn bolts with the same hand effort.

Torque Unit Conversion Reference

How to Use the Torque Converter

1. Enter the torque value: Type the number you want to convert. Decimals and very small/large numbers are fine.
2. Pick the source unit: Choose from N·m, ft·lb, in·lb, kgf·cm, kgf·m, dyn·cm, oz·in, or oz·ft.
3. Click Convert: All eight units appear at once. Click any card to copy that value to your clipboard.
4. Read the context panel: The Real-World Torque Context shows how your value compares to common applications such as a car lug nut or bike pedal — useful for sanity-checking specs.

Common Torque Specifications

• Eyeglass screw: ~0.05 to 0.1 N·m (very gentle)
• Smartphone or laptop screw: 0.1 to 0.3 N·m
• Bicycle stem bolt: 4 to 6 N·m (35 to 53 in·lb)
• Spark plug: 18 to 30 N·m (13 to 22 ft·lb)
• Car oil drain plug: 25 to 40 N·m (18 to 30 ft·lb)
• Car wheel lug nut: 80 to 130 N·m (60 to 100 ft·lb)
• Heavy truck wheel lug nut: 400 to 600 N·m (300 to 450 ft·lb)

Always follow the manufacturer's torque specification. Under-tightening risks loosening; over-tightening can strip threads, warp parts, or snap fasteners.

Torque vs Energy: Same Units, Different Meaning

Newton-meter (N·m) is also the SI unit of energy (1 N·m = 1 joule). To prevent confusion, torque is normally written as N·m (with the dot) while energy is written as J (joule). The same applies in imperial units: torque is ft·lb or lb·ft, while energy is ft·lbf (foot-pound-force). They have the same dimensions but represent different physical quantities — torque is a vector (force × perpendicular distance), while energy is a scalar (force × parallel displacement).

Frequently Asked Questions

How do I convert Nm to ft-lb?

Divide Newton-meters by 1.3558179 to get foot-pounds. For example, 100 N·m ÷ 1.3558179 ≈ 73.76 ft·lb. To go the other direction, multiply foot-pounds by 1.3558179 to get Newton-meters.

How do I convert kgf·cm to N·m?

Multiply kgf·cm by 0.0980665 to get Newton-meters. Example: 1000 kgf·cm = 98.0665 N·m. The factor comes from 9.80665 m/s² (standard gravity) divided by 100 cm per meter.

What's the difference between ft·lb and lb·ft?

They mean the same thing — the foot-pound torque unit. Engineering texts traditionally write it as lb·ft to distinguish torque from energy (foot-pound-force, ft·lbf). In automotive and tool catalogues, ft·lb and lb·ft are used interchangeably.

What torque is needed for car wheel lug nuts?

Most passenger cars require 80 to 130 N·m (60 to 100 ft·lb). Always check your owner manual for the exact specification — under-tightening risks the wheel coming loose, while over-tightening can warp brake rotors or strip threads.

Why are inch-pounds used instead of foot-pounds for small fasteners?

Inch-pounds (in·lb) are easier to read for low-torque values. 1 ft·lb = 12 in·lb, so a bicycle stem at 4.2 ft·lb is more naturally written as 50 in·lb. Electronics, optics, and bicycle specs typically use in·lb or N·cm.

Is kg·cm the same as kgf·cm?

Yes — kg·cm is informal shorthand for kgf·cm (kilogram-force × centimeter). It is widely used in Asian markets, especially for servo motors and small mechanical components. Strictly, the kilogram is a unit of mass; kgf-cm is the technically correct notation.

Additional Resources

• Torque - Wikipedia
• Newton-metre - Wikipedia
• Pound-foot (torque) - Wikipedia