Spring Rate in Compression Springs

• Compression Spring Design Resources – What Is Spring Rate & How to Determine Spring Rate?

Spring rate is the change in load per unit of deflection and may be determined using the following procedure:

1. Deflect* the spring approximated 20% of the available deflection and measure the load (P₁) and the height (L₁).
2. Deflect* the spring approximately 80% of the available deflection and measure the load (P₂) and the height (P₂).
3. Calculate the rate (lbs/inch) or (N/mm) by using the following formula:



R = (P2 - P1) / (L1 - L2)

*To deflect a spring one would apply or remove an external load, causing the spring ends/arms to move. Please contact the CSPI Spring facility nearest you for more information on spring rate and other considerations of spring design.