Foot-Pound to Joules Converter

A foot-pound to joules conversion translates a measurement of energy or work from the imperial system to the metric SI system. The foot-pound (ft-lb) is an imperial unit of energy defined as the work done by a force of one pound acting through a distance of one foot in the direction of the force. The joule (J) is the SI unit of energy, defined as the work done by a force of one newton acting through a distance of one meter. The conversion between these two units is exact: 1 foot-pound equals exactly 1.35582 joules.

The foot-pound is widely used in the United States for expressing torque in automotive and mechanical engineering, energy in physics problems, and work output in fitness equipment specifications. The joule is the universal standard in science, engineering, and international commerce. Converting between these units is essential when working with international specifications, scientific literature, or equipment from manufacturers that use different measurement systems.

This calculator also shows the equivalent value in newton-meters (N·m), which is numerically equal to joules for energy. In rotational mechanics, torque is often expressed in foot-pounds (ft-lb) or newton-meters (N·m), and the conversion factor between these units is the same as the foot-pound to joule conversion. This makes the converter useful for both energy calculations and torque conversions in mechanical engineering contexts.

The conversion uses the exact internationally agreed relationship between the foot-pound and the joule.

Use this calculator to convert foot-pounds to joules and newton-meters:

1. Enter the foot-pounds: Type the number of foot-pounds into the input field. You can use whole numbers, decimals, or very large values.
2. Read the primary result: The main result card shows the conversion to joules, computed as foot-pounds multiplied by 1.35582.
3. View the newton-meter equivalent: Below the primary result, you can see the same energy expressed in newton-meters (N·m), which has the same numerical value as joules for energy calculations.
4. Check common conversions: The quick reference table shows frequently used values: 1 ft-lb (1.356 J), 10 ft-lb (13.56 J), 100 ft-lb (135.58 J), and 1000 ft-lb (1,355.82 J).

The calculator updates in real time as you type, so you can try different values without pressing any buttons.

The calculator provides two equivalent energy measurements:

• Joules (J): The SI unit of energy. One joule equals the work done by a force of one newton acting through one meter. This is the universal standard for expressing energy in science and engineering.
• Newton-Meters (N·m): Numerically equal to joules for energy. However, in the context of torque, N·m is preferred over joules because torque is a rotational force, not energy per se, even though the dimensional analysis produces the same units. The converter shows both values because they are equal in magnitude.

For quick mental estimates, remember that 1 foot-pound is approximately 1.36 joules. A useful reference is that 100 foot-pounds equals about 135.6 joules, which is roughly the energy needed to lift a 100-pound weight about 1 foot off the ground.

This conversion is essential in automotive engineering, where engine torque is commonly expressed in foot-pounds in the United States but in newton-meters in most other countries. A car engine producing 300 ft-lb of torque generates approximately 406.7 N·m. International automotive specifications, racing regulations, and performance comparisons all require fluent conversion between these units.

In mechanical and structural engineering, work and energy calculations often begin with imperial measurements in US-based projects and must be reported in SI units for international publications or collaboration. The work done by a machine, the energy stored in a spring, or the kinetic energy of a moving object may be calculated in foot-pounds but needs to be expressed in joules for scientific papers and international standards.

In fitness and exercise science, exercise equipment specifications such as resistance levels, work output, and power ratings may be expressed in either foot-pounds or joules depending on the manufacturer. Understanding the conversion helps fitness professionals compare equipment across brands and communicate workout data in the preferred unit system. In physics education, converting between foot-pounds and joules is a fundamental exercise in unit conversion and dimensional analysis.