Z-Score Calculator
Calculate a z-score, standard deviation and percentile from raw data with this free z-score calculator that works straight in your browser.
100% FreeRuns in your browserBasic
Enter Values
Enter your values and press Calculate to see results.
How to use this calculator
- Enter a value, the mean and the standard deviation.
- Read the z-score and approximate percentile.
How it works
Z = (value − mean) ÷ standard deviation. The percentile assumes a normal distribution.
Worked example
x=85, μ=70, σ=10. Z = 1.5 (≈ 93rd percentile).
Tips
- Runs entirely in your browser. Your inputs are not saved or transmitted.
Frequently asked questions
What does a z-score mean?
How many standard deviations a value is above (+) or below (−) the mean.
Privacy?
Runs entirely in your browser. Your inputs are not saved or transmitted.
Related tools
- Normal Distribution Calculator
- Average (Mean) Calculator
- Binomial Probability Calculator
- Standard Deviation Calculator
- Confidence Interval Calculator
- Margin of Error Calculator
Explore more in Maths, Education & Science.
Cite this tool
Zerdly. (2026). Z-Score Calculator. Retrieved from https://www.zerdly.com/tools/z-score-calculator/
Tip: Enter any known values to calculate the remaining results.
Designed to run locally in your browser. Tool inputs are not intentionally stored by Zerdly unless stated otherwise.