The Spring Constant Calculator computes the stiffness kkk of a spring using either Hooke’s law (k=F/xk = F / xk=F/x) from a measured force and displacement, or from the period of small oscillations (k=4π2m/T2k = 4\pi^2 m / T^2k=4π2m/T2) using a known mass and oscillation period. It supports both metric and imperial units, converts values for display, and shows results in standard units (N/m and lbf/ft). This tool assumes an ideal linear spring and ignores damping — ideal for classroom demonstrations, lab work, and quick engineering checks.