Unit Converters · Free tool
Correlation Calculator
Compute Pearson's r between two paired number lists, plus r² and the t-statistic for testing rho = 0. Free online calculator with verbal interpretation.
Pearson r
r = 0.9971
Very strong positive correlation (8 paired points)
r² (variance explained)
0.9943
t-statistic (H₀: ρ=0)
32.3077
df
6
Tip: paste the t-statistic into the p-value calculator with df = 6 to test significance.
What r means and what it doesn't
r ranges from −1 (perfect inverse linear) to +1 (perfect positive linear). r = 0 means no linear relationship — but X and Y could still be related nonlinearly (think of a parabola).
r² tells you the proportion of variance in Y explained by a linear fit to X. r = 0.7 → r² = 0.49, so 49% of variance is accounted for.
Correlation is sensitive to outliers — one extreme point can flip the sign. Always plot your data before trusting r.
And: correlation is not causation. r doesn't tell you direction or mechanism.
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What it does
Compute Pearson's r between two paired numeric series — plus r² (variance explained) and the t-statistic for testing H₀: ρ = 0. r ranges from −1 (perfect inverse) to +1 (perfect positive); values near zero indicate no linear relationship.
The tool also gives a verbal interpretation (weak / moderate / strong) so you don't have to remember the rule of thumb. To test whether r is significantly different from zero, take the t-stat to the p-value calculator.
Embed this tool on your siteShow snippetHide
Paste this snippet into any page. Loads on-demand (lazy), no tracking scripts, and sized to most dashboards. Replace the height to fit your layout.
<iframe src="https://freetoolarena.com/embed/correlation-calculator" width="100%" height="720" frameborder="0" loading="lazy" title="Correlation Calculator" style="border:1px solid #e2e8f0;border-radius:12px;max-width:720px;"></iframe>How to use it
- Paste X values and Y values — comma, space, or newline separated.
- Lists must be the same length and have at least 3 pairs.
- Read r and r² — and note the verbal interpretation underneath.
- Use the t-statistic with df = n − 2 in the p-value calculator for hypothesis tests.
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