Spring Rate – Change This or That?

Spring rate is a key parameter of any spring. Spring rate is defined as the change in load per unit deflection, generally given in lbs/in or N/mm. A spring’s rate is primarily determined by design parameters including wire size, number of active coils, and coil diameter. 

Often, adjusting a spring’s rate—either increasing or decreasing it—can improve a product’s performance. Certain misconceptions exist regarding the effects of design modifications on spring rate. For example, increasing the number of coils results in a decrease in the spring rate, which is contrary to some common assumptions. The following chart demonstrates how basic design adjustments influence the spring rate.