Work from one pound-force over one foot.
Foot-pounds to Femtojoules Converter — ft-lb to fJ
Convert Foot-pound (ft-lb) to Femtojoule (fJ) using the exact conversion factor (1 foot-pound = 1.355818e+15 femtojoule). See the formula, worked examples, and conversion table.
Foot-pounds to Femtojoules 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.
Femtojoule is 1e-15 joule units.
Result = input x 1.355817948 / 1e-15.
Energy units are compatible.
Reserved above the conversion cards and below the converter.
About Converting Foot-pounds to Femtojoules
Foot-pound and Femtojoule 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 femtojoule is 1e-15 joule units.
Formula
femtojoules = foot-pounds × 1.355818e+15
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 femtojoule equals 1e-15 base units, so dividing one by the other gives the direct foot-pound-to-femtojoule factor of 1.355818e+15.
Simple example
1 ft-lb × 1.355818e+15 = 1.355818e+15 fJ
1 foot-pound = 1.355818e+15 femtojoules.
Real-world example
100 ft-lb × 1.355818e+15 = 1.355818e+17 fJ
100 foot-pounds = 1.355818e+17 femtojoules.
Conversion table
| Foot-pound (ft-lb) | Femtojoule (fJ) |
|---|---|
| 1 ft-lb | 1.355818e+15 fJ |
| 10 ft-lb | 1.355818e+16 fJ |
| 50 ft-lb | 6.77909e+16 fJ |
| 100 ft-lb | 1.355818e+17 fJ |
| 500 ft-lb | 6.77909e+17 fJ |
| 1,000 ft-lb | 1.355818e+18 fJ |
Reverse conversion: Femtojoule to Foot-pound
1.355818e+15 fJ × 7.375621e-16 = 1.000000038 ft-lb
1.355818e+15 femtojoules = 1.000000038 foot-pounds.
foot-pounds = femtojoules × 7.375621e-16
For a page dedicated to this direction, see Femtojoule to Foot-pound.
Understanding the Foot-pound (ft-lb)
Work from one pound-force over one foot.
Understanding the Femtojoule (fJ)
Femtojoule is 1e-15 joule units.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many femtojoules are in 1 foot-pound?
1 foot-pound equals 1.355818e+15 femtojoules, using the exact defined conversion factor rather than an estimate.
How do I convert foot-pound to femtojoule?
Multiply the foot-pound value by 1.355818e+15. The converter above does this instantly to whatever precision you set.
How do I convert femtojoule back to foot-pound?
Use the reverse factor: 1 femtojoule equals 7.375621e-16 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 femtojoule?
Femtojoule (fJ) is a unit of engineering.
Is the foot-pound to femtojoule conversion exact?
Yes. Both foot-pound and femtojoule are defined by fixed standards rather than physical artifacts, so the factor of 1.355818e+15 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.