Kilogram-force under standard gravity.
Kilogram-forces to Femtonewtons Converter — kgf to fN
Convert Kilogram-force (kgf) to Femtonewton (fN) using the exact conversion factor (1 kilogram-force = 9.80665e+15 femtonewton). See the formula, worked examples, conversion table, and common uses.
Kilogram-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 9.80665 / 1e-15.
Force units are compatible.
Reserved above the conversion cards and below the converter.
About Converting Kilogram-forces to Femtonewtons
Kilogram-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. Kilogram-force is most often used for appears on some older or legacy engineering and mechanical specifications, particularly torque wrenches and spring-force ratings, predating wider adoption of the newton.
Formula
femtonewtons = kilogram-forces × 9.80665e+15
This factor comes from each unit's defined relationship to the category's base unit: 1 kilogram-force equals 9.80665 base units, and 1 femtonewton equals 1e-15 base units, so dividing one by the other gives the direct kilogram-force-to-femtonewton factor of 9.80665e+15.
Simple example
1 kgf × 9.80665e+15 = 9.80665e+15 fN
1 kilogram-force = 9.80665e+15 femtonewtons.
Real-world example
100 kgf × 9.80665e+15 = 9.80665e+17 fN
100 kilogram-forces = 9.80665e+17 femtonewtons.
Conversion table
| Kilogram-force (kgf) | Femtonewton (fN) |
|---|---|
| 1 kgf | 9.80665e+15 fN |
| 10 kgf | 9.80665e+16 fN |
| 50 kgf | 4.903325e+17 fN |
| 100 kgf | 9.80665e+17 fN |
| 500 kgf | 4.903325e+18 fN |
| 1,000 kgf | 9.80665e+18 fN |
Reverse conversion: Femtonewton to Kilogram-force
9.80665e+15 fN × 1.019716e-16 = 1 kgf
9.80665e+15 femtonewtons = 1 kilogram-forces.
kilogram-forces = femtonewtons × 1.019716e-16
For a page dedicated to this direction, see Femtonewton to Kilogram-force.
Understanding the Kilogram-force
Kilogram-force (kgf) measures force. Defined as the force exerted by standard gravity on a mass of one kilogram — exactly 9.80665 newtons. It is classified as a non-SI unit, deprecated but still encountered.
Where it's used: Still encountered in some older European and Asian engineering specifications and torque-related equipment, though official use has been phased out in favor of the newton
Kilogram-force vs. newton. The newton is the modern SI unit of force; kilogram-force is an older, gravity-dependent unit still occasionally seen on legacy equipment. 1 kgf equals exactly 9.80665 N.
Uses of the Kilogram-force today
- Appears on some older or legacy engineering and mechanical specifications, particularly torque wrenches and spring-force ratings, predating wider adoption of the newton
Understanding the Femtonewton (fN)
Femtonewton is 1e-15 newton units.
Kilogram-force — sources
- BIPM SI Brochure — Notes kilogram-force among non-SI force units whose use is discouraged in favor of the newton.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many femtonewtons are in 1 kilogram-force?
1 kilogram-force equals 9.80665e+15 femtonewtons, using the exact defined conversion factor rather than an estimate.
How do I convert kilogram-force to femtonewton?
Multiply the kilogram-force value by 9.80665e+15. The converter above does this instantly to whatever precision you set.
How do I convert femtonewton back to kilogram-force?
Use the reverse factor: 1 femtonewton equals 1.019716e-16 kilogram-forces. You can also use the swap control in the converter above to flip the direction instantly.
What is a kilogram-force?
Kilogram-force (kgf) measures force. Defined as the force exerted by standard gravity on a mass of one kilogram — exactly 9.80665 newtons. It is classified as a non-SI unit, deprecated but still encountered.
What is a femtonewton?
Femtonewton (fN) is a unit of engineering.
Is the kilogram-force to femtonewton conversion exact?
Yes. Defined as the force exerted by standard gravity on a mass of one kilogram — exactly 9.80665 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 kilogram-force vs. newton?
The newton is the modern SI unit of force; kilogram-force is an older, gravity-dependent unit still occasionally seen on legacy equipment. 1 kgf equals exactly 9.80665 N.
Where is the kilogram-force still used today?
Still encountered in some older European and Asian engineering specifications and torque-related equipment, though official use has been phased out in favor of the newton