Skip to content
Free Tools Galaxy
🔗
100% free · no signupRuns in your browser

Correlation Coefficient Calculator

Pearson r with strength interpretation and R².

Best for: Use it to gauge how related two data series are before modelling or drawing conclusions.

Complete guide

Input

How it's calculated & sources
The Correlation Coefficient Calculator uses the standard, deterministic formula, so the same inputs always produce the same result. It runs entirely in your browser, so your inputs are never uploaded. Last reviewed June 2026.

Free & no sign-up · runs entirely in your browser. Results are estimates for general information, not professional advice — verify important decisions with a qualified expert. Last reviewed June 2026.

How it works

Pearson r = Σ(xᵢ−x̄)(yᵢ−ȳ) / √(Σ(xᵢ−x̄)² · Σ(yᵢ−ȳ)²). Range: −1 to +1.

Example

x=1..5, y=2,4,5,4,5 → r ≈ 0.775

Frequently asked questions

Correlation vs causation?+

Correlation measures linear association — it does not imply one variable causes the other.

Continue your journey

Where people usually head next.

📏
Significant Figures Calculator
Count significant figures in a number and round to a chosen number of sig figs.
🎯
Percent Error Calculator
Measure how far a measured value is from the true value, as a percentage.
🔬
Scientific Notation Converter
Convert numbers between standard decimal form and scientific (and E) notation.
🧪
Scientific Calculator
Evaluate expressions with sin, cos, log, ln, sqrt, π and e.

Complete guide

Quick answers

Short, sourced answers to the questions people (and AI assistants) ask most.

What is Correlation Coefficient?
A correlation coefficient calculator measures how strongly two variables move together, from -1 to +1 (Pearson's r).
Why does Correlation Coefficient matter?
r near +1 is a strong positive relationship, near -1 strong negative, near 0 little linear relationship. r only measures LINEAR association.
How is Correlation Coefficient calculated?
It divides the covariance of x and y by the product of their standard deviations. Formula: r = sum((x - xbar)(y - ybar)) / sqrt(sum((x - xbar)^2) x sum((y - ybar)^2)).
What are common correlation coefficient mistakes?
Reading correlation as causation.
When should you use the Correlation Coefficient Calculator?
Use it to gauge how related two data series are before modelling or drawing conclusions.

What is the Correlation Coefficient Calculator?

A correlation coefficient calculator measures how strongly two variables move together, from -1 to +1 (Pearson's r).

How the Correlation Coefficient Calculator works

It divides the covariance of x and y by the product of their standard deviations.

r = sum((x - xbar)(y - ybar)) / sqrt(sum((x - xbar)^2) x sum((y - ybar)^2))

Common mistakes to avoid

  • Reading correlation as causation.
  • Missing a strong non-linear relationship that r reports as weak.
  • Letting outliers inflate or hide the true relationship.

Keywords: correlation, pearson.

Sources: NIST/SEMATECH e-Handbook of Statistical Methods

Reviewed by the Free Tools Galaxy editorial team · Updated June 2026 · Calculated privately in your browser.

Frequently asked questions

Is the Correlation Coefficient Calculator free to use?+

Yes. Every tool on Free Tools Galaxy is 100% free, runs in your browser and requires no signup.

How accurate is the Correlation Coefficient Calculator?+

Correlation Coefficient Calculator uses the standard correlation coefficient formula in double-precision arithmetic, so the same inputs always produce the same result and you can verify any figure by hand. It is an educational estimate — real-world outcomes depend on your actual rates, rules and assumptions.

Do you store my inputs?+

No. The Correlation Coefficient Calculator runs entirely in your browser. Nothing is uploaded or saved to a server.

Can I use the Correlation Coefficient Calculator on mobile?+

Yes — the interface is fully responsive and works on phones, tablets and desktops.

What are common mistakes to avoid?+

The most frequent mistake is mixing units. Double-check your inputs use a single, consistent unit before clicking Calculate.

Explore more

Popular tools

📝
Word Counter
Count words, characters, sentences and reading time.
🔤
Case Converter
Convert text to UPPER, lower, Title and Sentence case.
🔁
Text Reverser
Reverse any text instantly.
🧹
Remove Duplicate Lines
Strip duplicate lines from any list.

Explore other categories

🧾
SSI Payment Calculator
Estimate your 2026 monthly Supplemental Security Income (SSI) from your income and living situation.
🏦
PPF Calculator
Project your Public Provident Fund maturity with a full year-by-year schedule.
💼
EPF Calculator
Estimate your Employees' Provident Fund corpus at retirement.
🧓
NPS Calculator
Project your National Pension System corpus, lump sum and monthly pension.
Related searches: logarithm calculator, combination calculator, square root calculator

Smart Autopilot

AI-style routing · 100% on-device

Based on this tool, your recent activity and how others chain tools together.

Likely next step

📏Significant Figures CalculatorTop match🎯Percent Error CalculatorMeasure how far a measured value is from the true value, as a percentage.🔬Scientific Notation ConverterConvert numbers between standard decimal form and scientific (and E) notation.🧪Scientific CalculatorEvaluate expressions with sin, cos, log, ln, sqrt, π and e.➕Simple CalculatorBasic arithmetic for two numbers: add, subtract, multiply, divide.½Fraction CalculatorAdd, subtract, multiply and divide fractions with auto-simplification.

Smart recommendations

Next best tool

log
Logarithm Calculator
log_b(x) for any base — common, natural or custom.

Also worth a look

📋
SGPA Calculator
Semester Grade Point Average for a single term.
💓
Target Heart Rate Calculator
Karvonen formula target HR zone for cardio.
❤️‍🔥
Heart Rate Zone Calculator
Five training zones from max heart rate.
📝
Word Counter
Count words, characters, sentences and reading time.

Share & publish

Share & challenge

Twitter Facebook LinkedIn WhatsApp
Share-to-grow kit (Reddit, LinkedIn, Medium)
Reddit post
Title: I built/used this free correlation coefficient calculator — instant, no signup

Body: Pearson r with strength interpretation and R². Try it: https://freetoolsgalaxy.com/tools/correlation-coefficient-calculator
LinkedIn post
Correlation Coefficient Calculator on Free Tools Galaxy — Pearson r with strength interpretation and R². https://freetoolsgalaxy.com/tools/correlation-coefficient-calculator
Medium intro
# Correlation Coefficient Calculator — the free tool I keep coming back to

Pearson r with strength interpretation and R².

Try it: https://freetoolsgalaxy.com/tools/correlation-coefficient-calculator
Quora answer
The fastest way is to use a free in-browser correlation coefficient calculator: https://freetoolsgalaxy.com/tools/correlation-coefficient-calculator. Pearson r with strength interpretation and R².

Embed this tool anywhere

Free embed code for blogs, docs and dashboards. Every embed sends a backlink home — helping you and the galaxy grow together.

HTML iframe
Drop into any site — auto-resizes to its content height, theme-aware.
<iframe src="https://freetoolsgalaxy.com/tools/correlation-coefficient-calculator?embed=1" title="Correlation Coefficient Calculator" loading="lazy"
  style="width:100%;height:600px;border:0;border-radius:16px;background:#0b1020"
  allow="clipboard-write"></iframe>
<script>window.addEventListener("message",function(e){if(e.data&&e.data.type==="ftg-embed-height"){document.querySelectorAll("iframe").forEach(function(f){if(f.contentWindow===e.source){f.style.height=e.data.height+"px";}});}});</script>
<p><a href="https://freetoolsgalaxy.com/tools/correlation-coefficient-calculator" target="_blank" rel="noopener">Powered by Correlation Coefficient Calculator on Free Tools Galaxy</a></p>
Responsive wrapper
Aspect-locked container — good for blog post bodies.
<div style="position:relative;padding-bottom:75%;height:0;overflow:hidden;border-radius:16px">
  <iframe src="https://freetoolsgalaxy.com/tools/correlation-coefficient-calculator?embed=1" title="Correlation Coefficient Calculator" loading="lazy"
    style="position:absolute;inset:0;width:100%;height:100%;border:0" allow="clipboard-write"></iframe>
</div>
WordPress / Markdown
Paste in a custom-HTML block or markdown file.
[Correlation Coefficient Calculator — free online tool](https://freetoolsgalaxy.com/tools/correlation-coefficient-calculator)

<iframe src="https://freetoolsgalaxy.com/tools/correlation-coefficient-calculator?embed=1" width="100%" height="600" frameborder="0"></iframe>
Text link-back
Minimal credit link — best for sidebars and footers.
<a href="https://freetoolsgalaxy.com/tools/correlation-coefficient-calculator" target="_blank" rel="noopener">Try the free Correlation Coefficient Calculator</a>

Share-to-Grow Kit

Pre-written, ready-to-paste posts for every major channel. Help others discover this tool — and earn backlinks.

Title
I built a free pregnancy due date calculator that works instantly in the browser — no signup, no ads in your face
Body
Hey r/[subreddit],

I kept needing a quick pregnancy due date calculator and most options online were slow or behind paywalls, so I built one that:

• Runs 100% in your browser (your data never leaves your device)
• No signup, no email wall, no popups
• Loads in under a second on mobile

It covers the standard pregnancy due date use cases (pregnancy, due, date, baby) and links out to the formula + worked examples if you want to learn the math.

Link: https://freetoolsgalaxy.com/tools/pregnancy-due-date-calculator

Happy to take feedback — what's missing?
Post to a relevant subreddit (e.g. r/InternetIsBeautiful, r/webdev, r/productivity). Avoid spammy subs.
Developer & SEO tools