🎲Cubic Equation Solver
Find all three roots of ax³ + bx² + cx + d = 0 using Cardano's formula, with steps.
Free Cubic Equation Solver
Cubic equations don't factor as neatly as quadratics. Our free cubic equation solver finds all three roots of any ax³ + bx² + cx + d = 0, using Cardano's formula, with the full derivation shown — not just the final answer.
Enter your four coefficients and the calculator depresses the cubic, computes the discriminant, and applies Cardano's formula step by step. The discriminant tells you what to expect: three distinct real roots, a repeated real root, or one real root paired with two complex conjugate roots — each case labelled clearly, with complex roots shown in standard a ± bi form.
A graph of the cubic is plotted alongside the algebra, with real roots marked where the curve crosses the x-axis. No sign-up, no downloads, no limits.