Torque: Foot-Pounds or Pound-Feet — Is There a Difference?

When discussing cars, enthusiasts often mention torque, horsepower, and other words you might’ve heard in physics class but never grasped. Car lovers understand the jargon behind vehicle performance, but the average driver might have no clue what it means. Let’s take a look under the hood and learn more about torque, including foot-pounds and pound-feet. 

Torque is rotational

Torque: Foot-Pounds or Pound-Feet — Is There a Difference?
Torque at work in a car burnout | Fairfax Media via Getty Images

Along with horsepower, torque is a primary measurement of a car’s drivetrain performance. J.D. Power explains the term clearly and concisely:

“Torque measures the twisting force, or strength, of an engine or motor. That sensation of being pushed back into your seat when you stomp on the accelerator? That’s torque. Illustrated using a non-automotive example, when opening a jar, torque is the effort with which you loosen the lid.”

Another visual: Think of opening a door. You instinctively push on the side farthest from the hinges. If you try pushing the door on the side closest to the hinges, you’ll need to apply much more force to open the door. Because people generally prefer to apply less force, the door handle is installed farther away from the hinges. 

According to Khan Academy, torque can be static or dynamic. The static kind doesn’t produce angular acceleration. You’re applying static torque when pushing on that door to open because it’s not rotating on its hinges despite the force you apply. Peddling a bike at a constant speed is also applying static torque because the bike is not accelerating. On the other hand, dynamic torque can be seen in a race car accelerating off the starting line. It’s producing an angular acceleration of the wheels as the car speeds up. 

So, now that you get the general idea, let’s go over foot-pounds and pound-feet.

What is the difference between foot-pounds and pound-feet?  

It would be easy to assume “foot-pounds” and “pound-feet” are interchangeable. The truth is they’re not synonymous. They are separate and distinct units of measure. They can be converted to each other, but that would require some complicated math. 

Pound-foot is a unit of torque and a vector measurement created by one pound of force acting on a one-foot lever, EngineLabs explains. You’ll see the plural form of the term, “pound-feet,” abbreviated in car performance specs, such as 250 lb-ft of torque.

However, foot-pound is “a measurement of work,” EngineLabs adds. “Work is the measurement of force over a given distance. So one foot-pound-force (ft-lbf or just ft-lb) is the energy required to move a one-pound object one foot of linear distance.”

Both foot-pounds and pound-feet have a force component (pounds) and a displacement component (feet), but they measure two different things. 

What’s the difference between torque and horsepower?  

“The measurement of torque is stated as pound-feet and represents how much twisting force is at work,” Edmunds explains. “If you can imagine a plumber’s pipe wrench attached to a rusty drainpipe, torque is the force required to twist that pipe.”

Torque moves your car at lower speeds, and the amount of torque also determines how quickly your vehicle can jump off a line from a standstill. Interestingly, once your car is moving, torque becomes less important, and horsepower needs to take over to maintain higher speeds. 

Horsepower is an easier-to-understand term regarding vehicles. You can envision horses running across the plains, but horsepower merely equals the amount of power required to perform 33,000 foot-pounds of work in one minute. We use horsepower to measure an engine’s or motor’s ability to produce power at higher speeds. You’ll see the term abbreviated as “hp” after a number, such as a 300-hp engine.

Once again, J.D. Power explains the difference between the two words best: “Simply put, torque gets you going, while horsepower keeps you moving.”

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