EVERYDAY CLARITY
Z-Score Calculator
Standardize a supplied observation using an explicit mean and standard deviation.
Your result
Z-score
Result for the values shown.
Calculations run in your browser.
What to enter
| Input | Meaning and units |
|---|---|
| Observation | Enter observation using the definition in the method and example. |
| Mean | Enter mean using the definition in the method and example. |
| Standard deviation | Enter standard deviation using the definition in the method and example. |
Understanding your result
Read Z-score in the units and model stated on this page. The formula z = (value - mean) / sd defines the relationship; measurement accuracy and model applicability are separate from numerical precision.
Common mistakes
- Using a different mathematical definition or operation than the one stated by this tool.
Check your calculation
- Use the worked example as a known reference case, then change one input at a time and check the direction and units of the response.
Calculation checks, sources and review limits
How many standard deviations above or below the mean is this value?
Standardize a supplied observation using an explicit mean and standard deviation.
Common uses
- How many standard deviations above or below the mean is this value
How it works
z = (value - mean) / sd
Worked example
Enter Observation: 120 ; Mean: 100 ; Standard deviation: 10 . Results: Z-score: 2 .