Z-Score Calculator
Calculate the z-score of a value using its mean and standard deviation, then interpret how far it sits from the average.
Formula: z = (x − mean) / standard deviation
Result will appear here.
| Metric | Value |
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Privacy: calculations run locally in your browser. No values are stored or transmitted.
How it works
A z-score standardizes a value relative to the dataset mean and spread.
Positive z means above the mean.
Negative z means below the mean.
Examples
- x = 85, mean = 70, sd = 10 → z = 1.5
- x = 60, mean = 70, sd = 10 → z = -1
- x = mean → z = 0
FAQ
- What is a z-score?
A z-score tells you how many standard deviations a value is above or below the mean.
- How is z-score calculated?
Use the formula z = (x − mean) / standard deviation.
- Why can't standard deviation be 0?
Because dividing by zero is undefined. If standard deviation is 0, there is no spread to standardize against.
- Are calculations stored?
No. Everything runs locally in your browser.