How many ft·lbf is 500 J?

500 ÷ 1.3558179 = 368.78 ft·lbf. About the energy to lift 370 pounds one foot.

A torque wrench is set to 100 ft·lbf — how many J?

100 × 1.3558179 = 135.6 J of rotational work.

Is ft·lbf exactly 1.356 J?

1 ft·lbf = 1 lb × 1 ft = (4.4482216152605 N) × (0.3048 m) = 1.3558179483 J. We typically use 1.356.

Why use ft·lbf instead of joules?

US mechanical engineering tradition — torque, horsepower, and machinery ratings have used ft·lbf for over a century.

Joules (J) to Foot-Pounds Force (ft·lbf) Converter

Enter a value to instantly convert between energy units.

From

Precision4 dp

1 Joule = 0.7376 Foot-Pound Force

Key Formulas

Kilocalorie → Kilojoule

kJ = kcal × 4.184

Kilojoule → Kilocalorie

kcal = kJ × 0.239006

Kilowatt-Hour → Joule

J = kWh × 3600000

Joule → Kilowatt-Hour

kWh = J × 2.77778e-7

Formula

ft·lbf = J ÷ 1.3558179

A foot-pound force is the work done by a force of one pound-force acting through one foot — about 1.356 joules. It's common in US mechanical engineering for torque wrenches, horsepwer ratings, and machinery specs. Converting from joules means dividing by 1.356.

Source: NIST SP 811, Table B.8

Frequently Asked Questions

Real-World Examples

A mechanical engineer checking that 1.356 J of work equals 1 ft·lbf for the spec sheet.

1.356 J = 1 ft·lbf

A motor rating of 100 J of work per rotation produces 73.76 ft·lbf of torque for the design doc.

100 J = 73.76 ft·lbf

An automotive engineer calculating 1000 J of kinetic energy in a crash test writes 737.56 ft·lbf in the report.

1000 J = 737.56 ft·lbf

A weightlifter pressing 50 J of work per rep converts to 36.88 ft·lbf for the US gym equipment comparison.

50 J = 36.88 ft·lbf

kcal to kj kj to kcal kwh to joules joules to kwh btu to joules calories to joules

Joules (J) to Foot-Pounds Force (ft·lbf) Converter

Key Formulas

Formula

Frequently Asked Questions

Real-World Examples

Related Converters