Torque measures the force that causes an object to rotate. It’s crucial in engineering and many other fields to get accurate torque measurements.
Newton-meters (Nm) are the standard unit for torque within the International System of Units (SI), but foot-pounds (ft-lbs) are also commonly used, especially in the United States. Sometimes, you need to convert Nm to ft-lbs, or vice versa.
This article will give you a simple and comprehensive guide to convert Nm to ft-lbs, so you can be sure you’re working with the right numbers.
Understanding Torque, Newton Meters, and Foot-Pounds
To convert Newton meters to foot-pounds, it helps to understand what each term means.
What is torque?
Torque is a measurement of the force that causes an object to rotate around an axis. It’s also called “moment of force” or “rotational force.”
The amount of torque depends on the magnitude of the force being applied and its distance from the axis of rotation.
What is a Newton meter?
A Newton meter (Nm) is the SI unit of torque. It’s the amount of torque that results from a force of one Newton applied at a 90-degree angle at a distance of one meter from the axis of rotation.
What is a foot-pound?
A foot-pound (ft-lb) is the imperial unit of torque. It’s the amount of torque that results from a force of one pound applied at a 90-degree angle at a distance of one foot from the axis of rotation.
Some engineers and scientists argue that the correct term for torque should be “pound-feet” (lb-ft) rather than “foot-pounds.” Arthur Mason Worthington suggested this terminology in his 1900 book, ‘Dynamics of Rotation.’ The Society of Automotive Engineers (SAE) also prefers the term “pound-feet.”
The conversion formula and its application
Converting between newton-meters and foot-pounds is actually quite simple. Here’s what you need to know.
Nm to ft-lbs
To convert newton-meters to foot-pounds, you’ll use this formula:
ft-lbs = Nm 0.73756 (or, if you prefer, ft-lbs = Nm 0.7376)
Here’s an example: To convert 50 Nm to ft-lbs, you’d multiply 50 Nm 0.73756 = 36.878 ft-lbs.
ft-lbs to Nm
To convert foot-pounds to newton-meters, use this formula:
Nm = ft-lbs / 0.73756 (or Nm = ft-lbs / 0.7376 or Nm = ft-lbs 1.3558 or Nm = ft-lbs 1.356)
For example, to convert 50 ft-lbs to Nm, you’d divide 50 ft-lbs / 0.73756 = 67.891 Nm.
Why accurate conversions are important
In fields like engineering, it’s crucial to make accurate conversions between units. Using the wrong units can cause miscalculations. When you’re working on an engineering project that involves different units of measurement, it’s essential to do the math correctly.
Conversion charts and common values
Here are a couple of handy conversion charts to help you quickly convert between newton-meters and foot-pounds.
Nm to ft-lbs conversion chart
Just multiply the number of newton-meters by 0.73756 to find the equivalent number of foot-pounds.
- 1 Nm = 0.73756 ft-lbs
- 2 Nm = 1.47512 ft-lbs
- 5 Nm = 3.6878 ft-lbs
- 10 Nm = 7.3756 ft-lbs
- 50 Nm = 36.878 ft-lbs
- 100 Nm = 73.756 ft-lbs
ft-lbs to Nm conversion chart
To convert from foot-pounds to newton-meters, multiply the number of foot-pounds by 1.3558.
- 1 ft-lb = 1.3558 Nm
- 5 ft-lbs = 6.779 Nm
- 10 ft-lbs = 13.558 Nm
- 50 ft-lbs = 67.89109 Nm
- 100 ft-lbs = 135.58 Nm
When would you convert Nm to ft-lbs?
Converting between Newton-meters and foot-pounds is common in any field that uses torque specifications. For example:
- Automotive engineers might use it to specify the correct torque for tightening bolts.
- Manufacturers might set torque limits on factory machinery.
- Aerospace engineers might calculate torque in aircraft engines.
Here’s a sample problem: Imagine a mechanic needs to tighten a bolt to 80 Nm, but their torque wrench reads in ft-lbs. What should they set the wrench to?
Answer: ft-lbs = 80 Nm 0.73756 = 59.0048 ft-lbs. The mechanic should set the wrench to about 59 ft-lbs.
Other Torque Units
While Newton-meters and foot-pounds are the most common units, you might also see torque expressed as:
- Kilogram-force centimeter (kgf-cm)
- Joules per radian (J/rad)
- Kilogram-meter (kgm)
Here are the conversion factors to Newton-meters:
- 1 kgf-cm = 0.09807 Nm
- 1 J/rad = 1 Nm
- 1 kgm = 9.80665 Nm
Conclusion
Understanding how to convert Newton-meters to foot-pounds is essential for applying the correct torque in various mechanical applications. Accurate conversions are key.
Remember, the formula to convert Nm to ft-lbs is: ft-lbs = Nm 0.73756. Use this information and the resources provided to ensure your torque calculations are precise and your projects are successful.