How it works
correlation calculator — the short version
The Correlation calculator (Pearson r) works out your correlation calculator in seconds, using the 2026 figures most UK households actually check against.
For a correlation calculator you can defend in a meeting, Correlation calculator (Pearson r) shows the figure AND the working. Copy the working, not just the number — that's where the conversation moves forward.
Getting the arithmetic right first time saves a re-do on paper. Write the formula at the top of the page — then crunch the numbers and the rest of this page explains what the answer means.
Compute Pearson’s correlation coefficient r between two data sets, with strength, direction and coefficient of determination R² explained.
On this page you will see Covariance, Pearson correlation and R squared treated as first-class terms — each one is linked to the calculators and references that use it, so you can follow the thread without retyping queries into a search bar.
If it helps, jump straight to the Maths hub or compare with the Standard Deviation Calculator and the Mean (Average) Calculator — those two calcs are the ones readers usually open right after this page.
From inputs to answer, in full
Consider a realistic scenario and follow it through:
Compute Pearson’s correlation coefficient r between two data sets, with strength, direction and coefficient of determination R² explained.
Moments this tool earns its keep
Correlation calculator (Pearson r) is aimed at people arriving with questions like these:
- "Pearson correlation formula"
- "R squared"
- "Correlation vs causation"
- "What is correlation calculator"
- "How to calculate correlation calculator"
- "Correlation calculator formula"
Where the number stops being useful
Every tool has an edge where it stops being the right answer. Correlation calculator (Pearson r) is no exception:
- For legally binding tax or medical decisions — cross-check with HMRC, NHS or a qualified professional.
- For very large or very small extremes the rounding error outgrows the useful precision.
- When the underlying rate or threshold has changed since the page was last reviewed — always verify with the primary source.
- When the input you have is already a derived figure (net of something) — feeding it in as "gross" will double-subtract.
Watch-outs before you trust the number
Every time you crunch the numbers for a new scenario, one of these creeps in — it's worth knowing them ahead of time.
- Misreading the unit in the label — 'per year', 'per month' and 'per day' versions of the same figure differ by 12× or 365×.
- Taking a ratio and multiplying it by the wrong side of the inputs — always write the ratio as A/B with labels before running.
- Trusting a screenshot of someone else’s calculation — rerun it yourself with the same inputs, numbers drift.
- Assuming percentages add up. 10% off then 10% more is not the original price — it is 99% of it.
- Not refreshing the page when thresholds are date-sensitive. If the page was cached yesterday, bank rates may already be yesterday’s.
The sources behind the numbers
Where the maths needs an external authority, we cross-check against:
- NIST
- Khan Academy
Works well alongside
If this question keeps coming up for you, the same cluster of tools usually comes next:
- Standard Deviation Calculator — Measure the spread of a data set with sample or population standard deviation.
- Mean (Average) Calculator — Add up your values and divide by how many there are — we show each step.
- Z-Score calculator — Convert a raw score into a z-score using z = (x − μ) / σ, plus the two-tailed p-value from the standard normal distribution.
How we keep this accurate
Our calculadoras run on pure, unit-tested functions — the same logic lives in the browser and in the CI test suite. When tax rates, thresholds or official figures move, the update lands within 24 hours of the announcement. You can read the editorial policy and corrections policy.
Found an out-of-date number on Correlation calculator (Pearson r) or anywhere else in the Maths toolkit? Send it to the editorial desk and we'll patch it. Or browse the full calculadora directory for the next tool you need.