Regression Calculator

It fits a straight line y = mx + b through your data points using ordinary least squares. You get the slope, intercept, equation, R squared, Pearson correlation r, standard error of the estimate, and the residual for each point. Add an x value and it also predicts the matching y.

At least 2 points with at least 2 different x values. With only 2 points you get a perfect fit by construction, so R squared equals 1 and the standard error is reported as 0. Standard error is most useful from about 5 or 6 points upward.

R squared is the share of the variance in y that the line explains, between 0 and 1. An R squared of 0.85 means the line explains 85 percent of the variation in your y values. The rest is scatter the line cannot capture.

Two reasons. Either you entered fewer than 2 valid points, or every x value is the same. A vertical line has an undefined slope under least squares, so the calculator returns no equation rather than a misleading one.

No. This tool is strictly linear regression. If your data follows a curve, transform it first (for example, take the log of y for exponential growth or use x squared for a parabola) and then fit a line to the transformed values.