Linear Regression Calculator — Line of Best Fit & Correlation

Use this free linear regression calculator to find the line of best fit for a set of data points. Paste your (x, y) pairs and you’ll get the least-squares equation y = mx + b, the correlation coefficient r and r², and a scatter plot with the line drawn through it.

How to use the calculator

1. Enter your data, one x, y pair per line.
2. Press Calculate.
3. Read the best-fit equation, the correlation, and see the scatter plot with the fitted line.

How the line of best fit works

The least-squares method finds the slope and intercept that minimize the total squared vertical distance from the points to the line: m = Σ((x − x̄)(y − ȳ)) / Σ((x − x̄)²) and b = ȳ − m·x̄. The correlation r measures how closely the points follow that line.

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Frequently asked questions

What is the line of best fit?

The straight line that minimizes the total squared vertical distance to your data points — the least-squares regression line y = mx + b.

What does the correlation coefficient r tell me?

How strongly the points follow a straight line: r near +1 or −1 means a strong linear relationship, while r near 0 means little or none.

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What is r²?

The square of the correlation. It’s the fraction of the variation in y explained by the line — for example r² = 0.73 means about 73%.

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