Above the mean
value = 85mean = 70stddev = 10
Result: z = 1.50 · percentile ≈ 93.32%
Z-Score Calculator
Compute the z-score of a value given the mean and standard deviation of the distribution, and see the corresponding percentile — the percentage of values expected to fall at or below it. Useful for comparing observations across different scales.
Enter your values and press Calculate — the result appears here.
Worked examples
Below the mean
value = 55mean = 70stddev = 10
Result: z = −1.50 · percentile ≈ 6.68%
Frequently asked questions
What is a z-score?
A z-score tells you how many standard deviations a value is from the mean. A z-score of 1.5 means the value is 1.5 standard deviations above the mean; −0.8 means 0.8 below. This lets you compare values from different distributions.
What does the percentile mean?
The percentile is the probability that a randomly drawn value is at or below yours, assuming a normal distribution. A z-score of 1.50 corresponds to about the 93.3rd percentile.
Can a z-score be negative?
Yes. Negative z-scores mean the value is below the mean. The percentile will be under 50% in that case.
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