Quadratic formula calculator
Solve a quadratic, including complex and repeated roots.
If a is zero, the tool handles the remaining linear equation. All-zero coefficients mean infinitely many solutions. Very large or ill-conditioned inputs remain subject to floating-point rounding. Change the input or settings to update your result. Results update as you type. Up to 1,000,000 characters.
Your result
How to use Quadratic formula calculator
- Enter the values you want to calculate and choose the relevant units or settings.
- The result updates as you type. Adjust the available settings if needed.
- Review the result, then use Copy result or a download link when available.
Useful next steps
How to use it
Write the equation as ax² + bx + c = 0, then enter its three coefficients. The discriminant b² - 4ac tells you whether the roots are real, repeated or complex.
A worked example
For x² - 5x + 6 = 0, enter 1, -5 and 6. The roots are 2 and 3. For x² + 1 = 0, the roots are i and -i.
What to know
If a is zero, the tool handles the remaining linear equation. All-zero coefficients mean infinitely many solutions. Very large or ill-conditioned inputs remain subject to floating-point rounding.