StatPakHow to make a correlation matrix in Google Sheets
A correlation matrix shows the Pearson correlation between every pair of columns. Example: the ad spend, price and sales data from the regression guide.
With the Correlation tool
Choose Correlation, select all three columns with headers (A1:C16), tick Labels and Run.
| Ad spend | Price | Sales | |
| Ad spend | 1 | ||
| Price | 0.006789903 | 1 | |
| Sales | 0.9598215 | -0.2546645 | 1 |
The matrix is lower-triangular because correlation is symmetric. The diagonal is always 1. Ad spend and sales correlate at 0.9598215, a strong positive relationship. Price and ad spend are only weakly related (0.006789903), which matters for regression: inputs that are strongly correlated with each other make coefficients unstable.
With CORREL
=CORREL(A2:A16, C2:C16) gives a single pair. For a full matrix of n columns you need n(n-1)/2 formulas, which is where the tool saves time. The Covariance tool works the same way and uses the population formula (divides by n), matching =COVARIANCE.P.