🧮 Math
Correlation Calculator
Enter two sets of numbers to calculate Pearson r correlation coefficient. Includes scatter plot and interpretation.
Pearson r
0.995546
r² (explained variance)
99.11%
Sample size (n)
10
Interpretation
Very strong positive correlation
[ Ad · 728×90 ]
Related Tools
Percentage Calculator
Calculate percentages, percentage change, and what percent o...
Random Number Generator
Generate random numbers in any range. Single number, list, o...
Standard Deviation Calculator
Paste a list of numbers and get mean, median, mode, variance...
Sample Size Calculator
Calculate the required sample size for any survey or experim...
Pearson correlation coefficient formula
r = Σ((x−x̄)(y−ȳ)) / √(Σ(x−x̄)² × Σ(y−ȳ)²)
Where x̄ and ȳ are the means of the X and Y datasets respectively.
Interpreting r values
- r = 1.0 — Perfect positive correlation
- r = 0.7 to 0.9 — Strong positive correlation
- r = 0.4 to 0.6 — Moderate positive correlation
- r = 0.1 to 0.3 — Weak positive correlation
- r = 0 — No linear correlation
- r = −0.1 to −0.9 — Negative correlation (same strengths)
r² (coefficient of determination)
r² tells you what percentage of the variation in Y is explained by X. An r of 0.8 means r² = 0.64 — so 64% of the variance in Y is explained by X.
Important limitation
Pearson r only measures linear correlation. Two variables can be strongly related in a non-linear way and still show r ≈ 0. Always visualise your data.