Standard Deviation Calculator
Enter your data values separated by commas
Result
Standard Deviation Calculator (σ) – Instant Results
Struggling to measure data spread? Just paste your numbers above and get Standard Deviation (σ), Mean, Variance, 95% Confidence Interval, and a Frequency Table in ONE second. Works on iPhone, Android, Mac, Windows – zero downloads, forever free!
What Is Standard Deviation? 60-Second Explanation
Standard Deviation (σ) shows how far numbers stray from the average. Low σ = tight group. High σ = wild scatter. Example: 48, 49, 50, 51 → σ ≈ 1.3 (super consistent). 10, 30, 70, 90 → σ ≈ 35 (huge variation).
Exactly What You Just Got (8 Pro Outputs)
In 0.3 seconds you received:
- σ (6 decimals) – Your headline risk number
- Mean – Classic average
- Count & Sum – Quick sanity check
- Variance – σ squared (for stats nerds)
- 95% CI – “True average is probably here”
- Live Steps – Every math line visible
- Frequency Table – Spot the most common value instantly
How to Use It (3 Steps)
- Paste numbers → comma separated
- Hit “Calculate”
- Copy or screenshot results
Why 2M+ Users Ditch Excel for This
| Feature | This Tool | Excel |
|---|---|---|
| Phone friendly | Yes | No |
| 1-click CI | Yes | 5 formulas |
| Live math steps | Yes | No |
| No file needed | Yes | No |
Real-World Uses
- Finance: Stock volatility
- Manufacturing: Quality control
- Education: Grade fairness
- Healthcare: BP variation
- Sports: Player consistency
95% Confidence Interval – Plain English
If you repeat your survey 100 times, 95 of those ranges will contain the real average. Perfect for polls, research, business forecasts.
Frequently Asked Questions
100% free?
Yes. No signup, no limits.
Works offline?
Save page → yes forever.
Decimals & negatives?
Yes – 3.14, -5.7, 0.001.
Data private?
100% in your browser.
Can I embed it?
Yes – WordPress, Wix, anywhere.