Torque Converter
Convert Newton-meters (Nm), pound-force feet (lbf·ft), kgf·m, and other torque units.
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Base Unit
Relative Value
*Diagram shows values relative to the selected base unit (Newton-meter).
Unit Information
What are Newton-meters (Nm)?
Newton-meter (symbol: Nm or N·m) is the SI derived unit of torque. One Newton-meter is the torque resulting from a force of one newton applied perpendicularly to the end of a moment arm that is one meter long. It is the standard unit for specifying torque in most engineering and scientific applications worldwide.
What are Newton-centimeters (Ncm) and Newton-millimeters (Nmm)?
These are smaller metric units of torque. 1 Nm = 100 Ncm = 1000 Nmm. They are used for specifying the torque of smaller motors, servos, and for tightening smaller fasteners where lbf-in or ozf-in might be used in the imperial system.
What are Kilonewton-meters (kNm)?
A kilonewton-meter is 1000 Newton-meters. This larger unit is used in heavy engineering applications, such as for specifying the torque of large industrial engines, ship propellers, or wind turbine gearboxes.
What are Dyne-centimeters (dyn·cm)?
The dyne-centimeter is the CGS (centimeter-gram-second) unit of torque. It is a very small unit used in older scientific literature or for delicate instruments. 1 Nm = 10,000,000 dyn·cm.
What are Kilogram-force meters (kgf·m)?
This is a gravitational metric unit. It represents the torque produced by a force equal to the weight of one kilogram (about 9.81 N) acting at a perpendicular distance of one meter. It is an older unit, sometimes seen in non-US, non-SI technical specifications.
What are Pound-force feet (lbf·ft)?
Pound-force foot (symbol: lbf·ft or ft·lbf), often informally called 'foot-pound', is an imperial and US customary unit of torque. It represents the torque created by one pound-force acting at a perpendicular distance of one foot from a pivot point. This unit is commonly used in the United States for specifying engine torque and fastener tightening specifications.
What are Pound-force inches (lbf·in) and Ounce-force inches (ozf·in)?
These are smaller imperial units of torque. 1 lbf·ft = 12 lbf·in. 1 lbf·in = 16 ozf·in. They are used for applications requiring less torque, such as small engines, tools, and robotics.
Formulas
τ = r × F
Torque (τ) is the cross product of the lever arm vector (r) and the force vector (F).
1 lbf·ft ≈ 1.3558 Nm
To convert pound-force feet to Newton-meters, multiply by approximately 1.3558.
1 Nm ≈ 0.73756 lbf·ft
To convert Newton-meters to pound-force feet, multiply by approximately 0.73756.
1 kgf·m ≈ 9.80665 Nm
One kilogram-force meter is approximately 9.80665 Newton-meters.
1 lbf·ft = 12 lbf·in
One pound-force foot is equal to 12 pound-force inches.
Power = Torque × Angular Velocity
The power output of a rotating system is the product of its torque and its angular speed.
Key Reference Points
- Tightening a jar lid: A few Newton-meters (Nm).
- Lug nuts on a car wheel: Typically 80-150 Nm (or 60-110 lbf·ft).
- Small car engine peak torque: 150-300 Nm (or 110-220 lbf·ft).
- Large diesel truck engine peak torque: Can exceed 2000 Nm (or 1500 lbf·ft).
- Torque from a typical power drill: 50-100 Nm.
- Torque from a small hobby servo motor: 1-10 kgf·cm.
- Torque required to turn a doorknob: 0.1-0.5 Nm.
- Stall torque of a V8 engine starter motor: ~20 Nm.
- Torque of a wind turbine main shaft: Can be in the range of thousands of kilonewton-meters (kNm).
- A high-end torque wrench for industrial use can measure up to 2000 lbf·ft or more.
Did You Know?
Although the units for torque (Newton-meter) are dimensionally the same as for work or energy (Joule, which is also N·m), torque and energy are very different physical concepts. Torque is a vector quantity representing a twisting force, while energy is a scalar quantity representing the capacity to do work. To avoid confusion, the unit 'Joule' is typically not used for torque.
The direction of the torque vector is determined by the right-hand rule. If you curl the fingers of your right hand in the direction of rotation caused by the force, your thumb points in the direction of the torque vector.
Engine torque represents the rotational force an engine can produce, while horsepower represents the rate at which it can do work. Both are important performance metrics, with torque often indicating low-speed pulling power and horsepower indicating high-speed performance.
Archimedes famously said, 'Give me a lever long enough and a fulcrum on which to place it, and I shall move the world.' This illustrates the principle of torque: a small force can create a large torque with a long enough lever arm.
Torque can cause a spinning object, like a gyroscope or a top, to precess. This is when the axis of rotation itself rotates, rather than just the object spinning faster or slower. It's a consequence of the conservation of angular momentum.
Impact wrenches deliver high torque by converting the inertia of a spinning hammer into short, powerful rotational blows. This allows them to loosen very tight bolts that would be difficult to turn with a standard wrench.
The gravitational forces between planets and their moons exert torques that can affect their rotation. For example, the torque from Earth's gravity has caused the Moon to become tidally locked, so it always shows the same face to Earth.
The tightness of a bottle cap is measured by its removal torque. The beverage industry uses specialized torque testers to ensure caps are sealed tightly enough to prevent leaks but not so tight that they are difficult for consumers to open.
If you try to tilt the axis of a spinning gyroscope, it will instead move in a direction perpendicular to your force. This counter-intuitive motion is called gyroscopic precession and is a direct result of torque acting on the angular momentum vector.
Stall torque is the maximum torque a motor can produce when it is not rotating (i.e., at zero speed). This is an important specification for applications that require high starting force, like robotics and winches.
Our muscles produce torque around our joints to create movement. For example, the bicep muscle exerts a force that creates a torque around the elbow joint to lift the forearm.
For a uniform gravitational field, an object's center of mass and center of gravity are the same. A force applied to the center of mass will cause linear acceleration without any torque, while a force applied elsewhere will cause both linear and angular acceleration.
The dyne-centimeter is the CGS unit of torque. It's a very small unit, often used in older physics texts or for describing the torque in very delicate scientific instruments.
A 'cheater bar' is a colloquial term for any pipe or extension used to increase the length of a wrench's handle. This increases the lever arm, allowing a person to apply a much greater torque to a stubborn nut or bolt.
Dynamic torque refers to the torque required to cause an angular acceleration of an object with a certain moment of inertia. This is distinct from static torque, which might be required to hold a load in place without moving.
For delicate applications like assembling electronics or firearms, a torque screwdriver is used. It can be set to 'slip' once a pre-set torque is reached, preventing over-tightening and damage to sensitive components.
A magnetic dipole (like a compass needle) in a magnetic field will experience a magnetic torque that tends to align it with the field. This is the principle behind electric motors.
Although dimensionally equivalent (force × distance), the Joule is reserved for energy and work, while the Newton-meter is used for torque. This is to avoid confusion, as torque is a vector quantity (with a direction of rotation) while energy is a scalar.