Torque conversion factor

1. Dec 20, 2005

Jdo300

Hello All,

This is sort of a dumb question but i'm looking around for the conversion factor between Newton-meters and foot pounds. I looked around at some of the many conversion calculators and some use abbreviations like lbf feet or poundal feet. Which one is actually foot pounds and whats the difference if there is one?

Thanks,
Jason O

2. Dec 20, 2005

FredGarvin

1 ft*Lbf = 1.356 N*m

As a note about conversions, if you know the conversions between Lbf to Newtons and feet to meters, then you can simply multiply them to get the conversion you are looking for.

$$(1 ft-Lb_f)(\frac{1 N}{.225 Lb_f})(\frac{.305 m}{1 ft}) = 1.356 N-m$$

I always use the Lbf notation which indicates pounds force as opposed to Lbm which is pounds mass. Most of the time it never matters between the two. I think it is good practice to make the distinction though.

Last edited: Dec 20, 2005
3. Dec 20, 2005

Jdo300

Thanks for the info. Is there a difference between the terms "foot-pound" and "poundal feet"?

Thanks,
Jason O

4. Dec 21, 2005

FredGarvin

The definition of a poundal is the unit of force equal to the force that produces an acceleration of one foot per second per second on a mass of one pound. It is not the same as a pound-force as above. The conversion is

1 pdl = 0.1383 N = (1/32.2) Lbf