Input:   Age   mo yr Height   cm in m

Results:   Z Score   Percentile     Decimal Precision: 0 1 2 3

 

Height for Age Percentile Interpretation

 

Percentile < 5:	Short stature
Percentile >= 5 and < 95:	Normal stature
Percentile >= 95:	Tall stature

In some cases, including consideration of pharmacotherapy, more stringent definitions of short or tall stature are used, with thresholds of < 3rd percentile or < 1st percentile for short stature, and > 97th or > 99th percentile for tall stature.
 
At the extremes (> 97th percentile or < 3rd percentile), small differences in percentiles represent clinically important differences in height. At these extremes, the z-score is a more precise reflection of how far the measurement deviates from the mean, and is a useful tool for tracking changes.
 
Examples
 

Z-score	Percentile equivalent
- 3.0	0.3
- 2.0	2.5
+ 2.0	97.5
+ 3.0	99.7

 

References

1. Percentile conversion from Z-Score is done by table look-up in the standard Normal Table. Percentiles are provided for Z Scores between -3.09 and 3.09. Values beyond these extremes return percentiles of 0.1 and 99.9 respectively.
2. Click for Normal Data Table
3. National health and nutrition survey (NHANES), CDC/National Center for Health Statistics. Click for LMS Parameters for Boys: Height for Age