Cubic Equation Solver

A cubic equation has the form ax³ + bx² + cx + d = 0 and always has three roots (which may be real or complex, and some may be repeated). Cardano\

The calculator uses the standard published formula for cubic equation. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.

This calculator works with inches. You can enter values in the units shown — the calculator handles all conversions internally.

The core formula is: Depress the cubic: substitute x = t − b/(3a) to eliminate the x² term. Each step in the calculation is shown so you can verify the result manually.