Calculate how many standard deviations a value is from the mean.
Statistical Parameters
Z-Score Analysis
1.00
Standard Score (z)
Indicates whether a score is above or below average and by how much.
Estimated Percentile84.1%
Deviation TypeAbove Mean
Your Score
-3σMean+3σ
About this calculator
What is a Z-Score?
The standard score (or z-score) is the number of standard deviations a given data point is above or below the mean of the population. A z-score of 0 is exactly at the mean, while a positive z-score is above the mean and a negative one is below.
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Pro Tips
z = 1 means the value is 1 standard deviation above the mean.
Approximately 95% of data in a normal distribution falls between z = -2 and z = 2.
The standard deviation (σ) must be greater than zero.
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Fun Facts
"Z-scores allow you to compare scores from different distributions (e.g., SAT vs ACT)."
"In the stock market, Z-scores are used in the 'Altman Z-Score' to predict the likelihood of bankruptcy."
"A z-score of 3 or higher is often considered an 'outlier' in many statistical contexts."
