How do I add a line of best fit to a scatter plot?

Choose "Linear" under Trendline. The fitted line is drawn dashed, and the equation y = mx + b with R² appears in the legend.

What is a good R² value?

It depends on the field. Calibration curves in analytical chemistry usually need R² ≥ 0.995. In biology or social sciences much lower values can still be meaningful. Always look at the plot as well as the number.

Can I plot a scatter graph from an Excel file?

Yes. Upload .xlsx or .xls and the first sheet is loaded. You can also copy cells from Excel and paste them.

No. Your data never leaves your browser. Plotiq parses and plots files locally with JavaScript, so nothing is uploaded to a server.

Scatter Plot Maker with Line of Best Fit

Plot X–Y data as a scatter plot and add a line of best fit with its equation and R². Ideal for correlation, calibration and lab data.

Series	n	Mean	Median	SD	SE	Min	Max
Absorbance	7	0.30143	0.297	0.21558	0.081483	0.002	0.602

Series	Model	Equation	Parameters	R²
Absorbance	linear	y = 0.04989x + 0.002071	b = 0.0020714, m = 0.049893	0.99980

How to use the Scatter Plot Maker

Paste your X and Y columns (first row = headers) or upload a CSV/Excel file.
Keep chart type on "Scatter".
Under Trendline choose "Linear" to get the line of best fit, equation and R².
Download the scatter plot as SVG, PDF or PNG.

Scatter plot with line of best fit

A scatter plot shows each observation as a single point, so you can see whether two variables are related. A line of best fit (least-squares regression line) summarises that relationship. Plotiq calculates the slope, intercept and coefficient of determination (R²) and prints them in the legend, so you can quote them in a report.

R² tells you how much of the variation in Y is explained by the fit. Values close to 1 mean the points lie close to the line. For a full list of regression statistics, check the results table under the chart.

Non-linear trendlines

Not every relationship is a straight line. Choose a 2nd or 3rd order polynomial for curved data, exponential for growth and decay, logarithmic for data that rises quickly then levels off, or power for allometric and scaling laws. Exponential and power fits ignore points with zero or negative Y, because those models cannot pass through them.

Comparing several groups

Add more Y columns to show several groups on the same axes. Each group gets its own marker shape (circle, square, triangle, diamond) so the plot stays readable in grayscale. A separate trendline is fitted for each group.

Frequently asked questions

How do I add a line of best fit to a scatter plot?: Choose "Linear" under Trendline. The fitted line is drawn dashed, and the equation y = mx + b with R² appears in the legend.
What is a good R² value?: It depends on the field. Calibration curves in analytical chemistry usually need R² ≥ 0.995. In biology or social sciences much lower values can still be meaningful. Always look at the plot as well as the number.
Can I plot a scatter graph from an Excel file?: Yes. Upload .xlsx or .xls and the first sheet is loaded. You can also copy cells from Excel and paste them.
Is my data private?: No. Your data never leaves your browser. Plotiq parses and plots files locally with JavaScript, so nothing is uploaded to a server.

Last updated: 1 November 2026 · by the Plotiq team