Z-Score Calculator
Compute standard scores, percentiles, and interpretations for any data point.
Results
Z-Score-
Percentile (approx.)-
Interpretation-
Formula Used-
What is a Z-Score?
A z-score (or standard score) measures how many standard deviations a data point is from the mean of a dataset. It is widely used in statistics, education, finance, and quality control to compare values from different distributions.
How to Use
- Choose Summary Stats if you already know the mean and standard deviation.
- Choose Full Dataset to let the tool auto-calculate the mean and standard deviation.
- Enter the required values and click Calculate.
Frequently Asked Questions
What does a z-score of 0 mean?
A z-score of 0 means the data point is exactly equal to the mean of the dataset.
What is a good z-score?
Generally, z-scores between -2 and +2 are considered typical. Scores beyond ±3 may be considered outliers.
How is percentile estimated?
The percentile is estimated from the standard normal cumulative distribution function (CDF) associated with the calculated z-score.
Can I use sample standard deviation?
Yes. Enter your sample or population standard deviation directly in the Summary Stats tab.