LMS method
The LMS method describes a growth reference using three age-specific parameters — L for skewness, M for the median and S for variation — which together allow any measurement to be converted into a Z-score and a percentile.
Example
Z = ((X/M)^L − 1) / (L·S), with the special case ln(X/M)/S when L is zero. The CDC and WHO charts both publish LMS tables.