Z-score
Express an observation in standard deviations from the mean.
How this works
z = (x − mean)/standard deviation. Percentile assumes a normal distribution.
Example
Using the example inputs, z-score is 1.5.
- Observation
- 85
- Mean
- 70
- Standard deviation
- 10
- Z-score
- 1.5
Scope and assumptions
Uses your inputs only; results are rounded for display.
NIST statistical methods handbook