Calculate Pearson correlation from raw observations. Select numeric variables, inspect their pairwise relationships, and export a labeled matrix with a fixed −1 to +1 scale.
CSV, TSV, XLS/XLSX or pasted cells. Your spreadsheet contents stay on this device.
Start with your table or try the sample
Raw observations in 2–12 numeric columns
No account or server-side file processing.
Input requirements
Give the chart the right data
Supply at least three complete observations and select 2–12 numeric columns. Each row must describe the same observation across all selected variables. Blank cells, non-numeric values, and constant columns block calculation. Pre-calculated matrices belong in Heatmap instead.
Maximum import: 10 MB, 2,000 rows including the header, 100 columns, and 20,000 cells. This tool accepts zero or absolute numeric values between 10⁻⁹ and 10¹²; rescale extreme values first. Excel imports read the first worksheet.
Choose deliberately
When to use a correlation matrix
Explore pairwise linear relationships among measurements. Values near +1 indicate positive linear association, values near −1 negative association, and values near 0 weak linear association.
When to choose another chart
Pearson r does not establish causation, rule out nonlinear relationships, or show statistical significance. Outliers and small samples can dominate the result. IDs and arbitrary numeric category codes are usually inappropriate variables.
From table to figure
Three steps to a useful chart
Import and review
Upload a spreadsheet, paste cells, or load fictional sample data. Review the automatically selected fields and correct them if necessary.
Read and refine
Inspect the values and any data warnings. Choose a publication style, canvas, title, and source note.
Export your result
Download editable SVG or PNG at 1×, 2×, or 3×. The original spreadsheet contents stay in your browser.
Before you create your chart
How is this different from the Heatmap tool?
This page calculates Pearson r from selected raw numeric columns and validates complete observations. Use Heatmap to visualize an existing matrix or X/Y/Value table.
Why is a constant column rejected?
A variable with no variation has undefined Pearson correlation. Remove it from the selection or provide observations that vary.
Are missing values automatically filled?
No. All selected fields must be complete. Correct the named row and column or explicitly prepare a complete dataset before importing.
Does Charttoolbox upload my data?
Spreadsheet contents are parsed, calculated, and rendered locally. Optional Google Analytics loads only after consent and does not receive filenames, spreadsheet contents, or generated chart data.
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