This spring rate converter converts spring stiffness between lbf/in, lbf/ft, kips/in, kips/ft, N/m, N/mm, kg/mm, and J/m² units.
Physics
Spring Rate Converter
Convert spring rate between lbf/in, lbf/ft, kips/in, kips/ft, N/m, N/mm, kg/mm and J/m².
Calculator
About this calculator
Formula notes
1 lbf/in = 175.126836986 N/m; 1 N/mm = 1000 N/m; other factors are derived from these exact unit definitions.
Worked examples
- Example: 10 lbf/in equals about 1751.27 N/m or 1.75 N/mm.
- A spring rate of 100 lbf/in equals approximately 17,512.68 N/m or 17.51 N/mm.
How to use it
- Enter a spring rate in any supported unit.
- The other fields update to the equivalent values.
- Use the result in your suspension or mechanical calculation.
Frequently asked questions
What is spring rate?
Spring rate is the force required to compress or extend a spring by a unit of distance, commonly expressed in N/m or lbf/in.
Is lb/ft converted to lbf/in accurately?
Yes, the converter uses exact unit relationships such as 1 ft = 12 in and 1 kip = 1000 lbf.
Limits and interpretation
- Conversion uses exact unit definitions, but real spring measurements may vary due to material and manufacturing tolerance.
- J/m² is not a stiffness unit in the common sense; it appears in the converter only because the source definition exposed it.