Z-score Standardization Calculator
Express an observation as a signed number of standard deviations from a mean.
Your result
MATHEnter your values and select calculate.
On this page How it works & practical examples
How to use the Z-score Standardization Calculator
Use a mean and standard deviation from the same reference group as the observation. Positive scores are above that mean; negative scores are below it.
The calculation
Worked example
An observation of 85, mean 70 and standard deviation 10 give z = 1.5.
Assumptions and limits
No probability or percentile is inferred because a z-score alone does not prove a normal distribution. A zero standard deviation cannot standardize observations.
Common questions
Which inputs should I use?
Use a mean and standard deviation from the same reference group as the observation. Positive scores are above that mean; negative scores are below it.
What does the result exclude?
No probability or percentile is inferred because a z-score alone does not prove a normal distribution. A zero standard deviation cannot standardize observations.