Work from one pound-force over one foot.
Foot-pounds to Kilojoules Converter — ft-lb to kJ
Convert Foot-pound (ft-lb) to Kilojoule (kJ) using the exact conversion factor (1 foot-pound = 0.0013558179 kilojoule). See the formula, worked examples, and conversion table.
Foot-pounds to Kilojoules converter
Converter
Engineering Converter
Convert common stress, force, torque, power, and energy units used in engineering.
Context values
Some unit families need one extra value for a physically accurate result.
Kilojoule is 1000 joule units.
Result = input x 1.355817948 / 1000.
Energy units are compatible.
Reserved above the conversion cards and below the converter.
About Converting Foot-pounds to Kilojoules
Foot-pound and Kilojoule both measure a quantity used in structural or mechanical engineering — commonly stress, pressure, force, torque, power, or energy — where converting between the unit conventions used in different regions, industries, or equipment specifications is a routine part of design work. Specifically: Work from one pound-force over one foot, and kilojoule is 1000 joule units.
Formula
kilojoules = foot-pounds × 0.00135581794833
This factor comes from each unit's defined relationship to the category's base unit: 1 foot-pound equals 1.35581794833 base units, and 1 kilojoule equals 1000 base units, so dividing one by the other gives the direct foot-pound-to-kilojoule factor of 0.00135581794833.
Simple example
1 ft-lb × 0.001355817948 = 0.0013558179 kJ
1 foot-pound = 0.0013558179 kilojoules.
Real-world example
100 ft-lb × 0.001355817948 = 0.1355817948 kJ
100 foot-pounds = 0.1355817948 kilojoules.
Conversion table
| Foot-pound (ft-lb) | Kilojoule (kJ) |
|---|---|
| 1 ft-lb | 0.0013558179 kJ |
| 10 ft-lb | 0.0135581795 kJ |
| 50 ft-lb | 0.0677908974 kJ |
| 100 ft-lb | 0.1355817948 kJ |
| 500 ft-lb | 0.6779089742 kJ |
| 1,000 ft-lb | 1.355817948 kJ |
Reverse conversion: Kilojoule to Foot-pound
0.0013558179 kJ × 737.5621493 = 0.9999999644 ft-lb
0.0013558179 kilojoules = 0.9999999644 foot-pounds.
foot-pounds = kilojoules × 737.562149277
For a page dedicated to this direction, see Kilojoule to Foot-pound.
Understanding the Foot-pound (ft-lb)
Work from one pound-force over one foot.
Understanding the Kilojoule (kJ)
Kilojoule is 1000 joule units.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many kilojoules are in 1 foot-pound?
1 foot-pound equals 0.0013558179 kilojoules, using the exact defined conversion factor rather than an estimate.
How do I convert foot-pound to kilojoule?
Multiply the foot-pound value by 0.001355817948. The converter above does this instantly to whatever precision you set.
How do I convert kilojoule back to foot-pound?
Use the reverse factor: 1 kilojoule equals 737.5621493 foot-pounds. You can also use the swap control in the converter above to flip the direction instantly.
What is a foot-pound?
Foot-pound (ft-lb) is a unit of engineering.
What is a kilojoule?
Kilojoule (kJ) is a unit of engineering.
Is the foot-pound to kilojoule conversion exact?
Yes. Both foot-pound and kilojoule are defined by fixed standards rather than physical artifacts, so the factor of 0.001355817948 used above is exact to as many digits as you choose to display.
Why do engineering unit conventions vary so much by region and industry?
Pressure, force, and stress can be expressed in metric (pascal, newton), US customary (psi, pound-force), or older and industry-specific units (atmosphere, torr, kip) depending on the country, industry, and even the equipment manufacturer, which is why engineers routinely need to convert between them when working across specs from different sources.