Growth guide
How to read SDS and percentiles
Plain-language context for two ways of describing a height-for-age reference position.
Two views of the same reference
An SDS describes distance from the reference median in standard-deviation units. A percentile expresses the relative position on a 0–100 scale.
Neither number is a score for a child, a ranking, or a prediction of what will happen next.
Keep the limits visible
Values are sensitive to the selected reference, age, date, and measurement. They are most useful when interpreted as one part of a record over time.
If a verified reference is unavailable, the honest result is unavailable—not an improvised number.