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Energy Foot Pounds Calculator

Calculates foot pounds using Work (ft-lb) = Force (lb) x Distance (ft), instantly in your browser.

Last updated: July 2026 · Free · No sign-up required

kg
m/s²
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Enter values above and click Calculate to see your result instantly.

About the Energy Foot Pounds Calculator

Behind the inputs above sits one rule: Work (ft-lb) = Force (lb) x Distance (ft); 1 ft-lb = 1.35582 J. The tool evaluates it instantly with the values you enter.

If you are new to foot pounds calculator, start with the worked example in the methodology section below — it walks the formula end-to-end with real numbers — then use the quick-reference table for common scenarios.

Quick reference

Convert foot-poundsEquals
1 ft·lb1.35582 joules
1 ft·lb0.001285 BTU
1 joule0.73756 ft·lb
1 ft·lb/s1.35582 watts

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Below the calculator we link a small set of plain-English explainer pages — "What is a percentage?", "Why does PEMDAS matter?", and so on. They cover the underlying concept in 4–6 short paragraphs. Read those before the calculator if the topic is new, or after if you want the extra context.

Interpretation guide

QuantityFormula (US units)
Work (energy)W = force (lb) x distance (ft)
TorqueT = force (lb) x lever arm (ft)
Powerft·lb per second or minute

Formula & methodology

Formula: Work (ft-lb) = Force (lb) x Distance (ft); 1 ft-lb = 1.35582 J

How foot-pounds of energy are calculated

A foot-pound of work is the energy used to move a 1-pound force through 1 foot. Multiply the force by the distance moved in the direction of the force.

Example

Lifting a 50-lb weight 4 feet: W = 50 x 4 = 200 ft·lb. In SI that is 200 x 1.35582 = 271.2 joules.

Note that foot-pound (energy/torque) and pound-foot are dimensionally the same unit but describe different physics — energy when force acts over a distance, torque when force acts on a lever arm. Always confirm which one a spec means.

Frequently asked questions

What is a foot-pound?
A foot-pound (ft·lb) is a unit of work or energy in the US customary system — the energy needed to move a force of one pound through a distance of one foot. It equals about 1.356 joules. The same unit name is also used for torque, where it means a pound of force on a one-foot lever arm.
How do you calculate foot-pounds of energy?
Multiply the force in pounds by the distance moved in feet, in the direction of the force: work = force x distance. Lifting a 25-lb box 6 feet does 25 x 6 = 150 ft·lb of work. Only motion along the force direction counts.
How do you convert foot-pounds to joules?
Multiply foot-pounds by 1.35582 to get joules. So 100 ft·lb = 135.6 J. To go the other way, multiply joules by 0.73756 to get foot-pounds. The conversion comes from combining the pound-force and foot definitions in SI units.
Is a foot-pound the same as a pound-foot?
They share the same dimensions but describe different things by convention. 'Foot-pound' (ft·lb) usually denotes energy or work — force acting through a distance. 'Pound-foot' (lb·ft) usually denotes torque — force acting on a lever arm. Many sources use them loosely, so always check the context.
What is foot-pounds used for?
Foot-pounds measure mechanical work and energy in US engineering — lifting loads, the muzzle energy of bullets, the output of engines, and the tightening torque of bolts (as pound-feet). It is the customary counterpart to the joule, and conversions between the two are common in technical work.
How is foot-pound energy calculated from weight and velocity?
E(ft·lb) = weight(grains) × velocity(fps)² ÷ 450,240. A 55-grain projectile at 3,100 fps carries 55 × 3,100² ÷ 450,240 ≈ 1,174 ft·lb. The divisor bundles the grain-to-slug mass conversion with the ½ in ½mv² — enter the two numbers and the calculator handles it.

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