The spring potential energy formula calculates the energy stored in a compressed or stretched spring. This energy is given by the formula $$U = \frac{1}{2} k x^2$$, where $$U$$ is the potential energy, $$k$$ is the spring constant, and $$x$$ is the displacement from the equilibrium position. This concept highlights how mechanical energy is stored in elastic materials and is crucial for understanding energy conservation in systems involving springs.