Pound-force under standard gravity.
Pound-forces to Femtonewtons Converter — lbf to fN
Convert Pound-force (lbf) to Femtonewton (fN) using the exact conversion factor (1 pound-force = 4.448222e+15 femtonewton). See the formula, worked examples, conversion table, history, and common uses.
Pound-forces to Femtonewtons 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.
Femtonewton is 1e-15 newton units.
Result = input x 4.448221615 / 1e-15.
Force units are compatible.
Reserved above the conversion cards and below the converter.
About Converting Pound-forces to Femtonewtons
Pound-force and Femtonewton 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. Pound-force is most often used for us engineering and aerospace force specifications.
Formula
femtonewtons = pound-forces × 4.448222e+15
This factor comes from each unit's defined relationship to the category's base unit: 1 pound-force equals 4.44822161526 base units, and 1 femtonewton equals 1e-15 base units, so dividing one by the other gives the direct pound-force-to-femtonewton factor of 4.448222e+15.
Simple example
1 lbf × 4.448222e+15 = 4.448222e+15 fN
1 pound-force = 4.448222e+15 femtonewtons.
Real-world example
100 lbf × 4.448222e+15 = 4.448222e+17 fN
100 pound-forces = 4.448222e+17 femtonewtons.
Conversion table
| Pound-force (lbf) | Femtonewton (fN) |
|---|---|
| 1 lbf | 4.448222e+15 fN |
| 10 lbf | 4.448222e+16 fN |
| 50 lbf | 2.224111e+17 fN |
| 100 lbf | 4.448222e+17 fN |
| 500 lbf | 2.224111e+18 fN |
| 1,000 lbf | 4.448222e+18 fN |
Reverse conversion: Femtonewton to Pound-force
4.448222e+15 fN × 2.248089e-16 = 1.000000086 lbf
4.448222e+15 femtonewtons = 1.000000086 pound-forces.
pound-forces = femtonewtons × 2.248089e-16
For a page dedicated to this direction, see Femtonewton to Pound-force.
Understanding the Pound-force
Pound-force (lbf) measures force. A pound-force is the force exerted by standard gravity on one pound-mass: exactly 4.4482216152605 newtons. It is classified as a US/imperial customary unit.
Where it's used: United States (engineering, aerospace)
Pound-force vs. pound-mass. Pound-force (lbf) measures force, while the plain 'pound' almost always refers to pound-mass; the two are related by standard gravity, not identical — a common source of confusion in US engineering units.
Uses of the Pound-force today
- US engineering and aerospace force specifications
- Torque and pressure units derived from it (psi, foot-pounds)
- Automotive and mechanical specifications
History of the Pound-force
Pound-force was defined to let US engineers keep using the familiar pound in force calculations, fixed via standard gravity (9.80665 m/s²) acting on one pound-mass, once the pound-mass itself was standardized in 1959.
Historical origin. Pound-force was not the invention of a single named person; it developed through the process described above.
Understanding the Femtonewton (fN)
Femtonewton is 1e-15 newton units.
Pound-force — sources
- NIST Special Publication 811 — Documents the pound-force definition via standard gravity.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many femtonewtons are in 1 pound-force?
1 pound-force equals 4.448222e+15 femtonewtons, using the exact defined conversion factor rather than an estimate.
How do I convert pound-force to femtonewton?
Multiply the pound-force value by 4.448222e+15. The converter above does this instantly to whatever precision you set.
How do I convert femtonewton back to pound-force?
Use the reverse factor: 1 femtonewton equals 2.248089e-16 pound-forces. You can also use the swap control in the converter above to flip the direction instantly.
What is a pound-force?
Pound-force (lbf) measures force. A pound-force is the force exerted by standard gravity on one pound-mass: exactly 4.4482216152605 newtons. It is classified as a US/imperial customary unit.
What is a femtonewton?
Femtonewton (fN) is a unit of engineering.
Is the pound-force to femtonewton conversion exact?
Yes. A pound-force is the force exerted by standard gravity on one pound-mass: exactly 4.4482216152605 newtons. That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.
What is the difference between pound-force vs. pound-mass?
Pound-force (lbf) measures force, while the plain 'pound' almost always refers to pound-mass; the two are related by standard gravity, not identical — a common source of confusion in US engineering units.
Where is the pound-force still used today?
United States (engineering, aerospace)