Scatter Plot Maker

Create scatter plots with trend lines in seconds — no signup, no server uploads. Paste your X,Y data pairs or upload a CSV file, and this tool instantly renders an interactive scatter plot with optional linear regression. See the best-fit line equation and R² value calculated right in your browser. Perfect for students, data analysts, researchers, and anyone who needs to visualize the relationship between two variables quickly.

What is a scatter plot and when should I use one?

A scatter plot displays data points on an X-Y axis to show the relationship between two variables. Use one when you want to see if two variables are correlated — for example, advertising spend vs. revenue, study hours vs. test scores, or temperature vs. ice cream sales. Each dot represents one data pair. Patterns in the dots reveal positive correlations (dots trend upward), negative correlations (dots trend downward), or no correlation (dots are scattered randomly).

What does the trend line and R² value tell me?

The trend line (linear regression) shows the best-fit straight line through your data. The equation y = mx + b tells you the slope (m) and intercept (b). R² (R-squared) measures how well the line fits your data — 1.0 means a perfect fit, 0.0 means no linear relationship at all. An R² above 0.7 generally indicates a strong linear correlation, while values below 0.3 suggest the relationship is weak or non-linear.

How is the linear regression calculated?

This tool uses the ordinary least squares method. The slope is calculated as (n*Σxy - Σx*Σy) / (n*Σx² - (Σx)²), and the intercept as (Σy - slope*Σx) / n. R² is computed as 1 - (SS_res / SS_tot), where SS_res is the sum of squared residuals and SS_tot is the total sum of squares around the mean. All calculations run entirely in your browser — no data is sent to any server.