Z-score calculator
See how many standard deviations a value sits above or below the mean.
The formula is (value minus mean) divided by standard deviation. Standard deviation must be positive. Inputs are limited to magnitude 1 trillion. The result describes standardized distance, not a probability; no normal-distribution assumption is applied. Change the input or settings to update your result. Results update as you type. Up to 1,000,000 characters.
Your result
How to use Z-score calculator
- Enter the observed value, the dataset mean and its standard deviation. A positive score is above the mean, a negative score is below it and zero is exactly at the mean.
- An observed value of 115, a mean of 100 and a standard deviation of 15 give a z-score of 1. The observation is one standard deviation above the mean.
Useful next steps
Compare a value with its dataset
Enter the observed value, the dataset mean and its standard deviation. A positive score is above the mean, a negative score is below it and zero is exactly at the mean.
Try a small example
An observed value of 115, a mean of 100 and a standard deviation of 15 give a z-score of 1. The observation is one standard deviation above the mean.
What to know
The formula is (value minus mean) divided by standard deviation. Standard deviation must be positive. Inputs are limited to magnitude 1 trillion. The result describes standardized distance, not a probability; no normal-distribution assumption is applied.