Z-score Calculator
Calculate Z-scores and visualize normal distribution
Calculator
Results
Mean
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Standard Deviation
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Z-score Values
| Data Point | Value | Z-score |
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Selected Z-score
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Enter data and click calculate to see results
Normal Distribution
Probability (P-value)
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Percentile
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What is a Z-score?
A Z-score (standard score) represents the number of standard deviations a data point is from the mean of a distribution.
Z = (X – μ) / σ
Where:
- Z is the Z-score
- X is the value of the element
- μ is the population mean
- σ is the standard deviation
Z-scores are useful for comparing data points from different normal distributions and identifying outliers.
Interpretation Guide
- Z-score of 0 = value is exactly at the mean
- Z-score of ±1 = value is 1 standard deviation from the mean
- Z-score of ±2 = value is 2 standard deviations from the mean
- Z-score of ±3 = value is 3 standard deviations from the mean