springs are everywhere, for your favorite childhood toy the slinky to clicking your pen as an adult to sign a bill. No matter what kind of spring it is or how it is being used doesn't matter when trying to calculate the spring force. The spring force is the force put on the string eating it to stretch or contract from equilibrium. Equilibrium is when forces are at balance and the spring is in its happy place. The spring force (Fs) is equal to the spring Constant(K) times the Displacement(X). The spring constant is measured in Joules this is a N(M). A joule is also equal to Kg m^2 / s^2. X is equal to displacement. This is the displacement from equilibrium. In a Spring force and displacement graph the area under the line in the graph is equal to the force exerted on the spring.