Quadratic Regression Calculator
Fit a quadratic curve of the form y = ax^2 + bx + c through your data points using least squares regression.
What quadratic regression does
Quadratic regression fits a parabola (a curve of the form y = ax^2 + bx + c) through a set of data points, choosing the a, b, and c coefficients that minimize the total squared distance between the curve and your actual data.
How this calculator works
Enter at least three x,y data points. The calculator builds the least-squares normal equations for a quadratic fit and solves them directly using Cramer’s rule (determinants), giving you the exact a, b, and c coefficients. It also reports R-squared, which tells you how much of the variation in y is explained by the fitted curve — closer to 1 means a better fit.
Quadratic regression works well when your data follows a single curved bend (like projectile motion or a U-shaped relationship). If your data has more than one bend, a higher-degree polynomial fit may work better. Provided for general educational purposes.