Baby Height Percentile Calculator (WHO Length/Height-for-Age 0–5 Years)
Find your baby’s or toddler’s length or height percentile and z-score from the WHO growth standards, from birth to 5 years, with the median, normal range and stunting check.
How it works
z = (length ÷ M − 1) ÷ S (WHO LMS method with L = 1) · percentile = Φ(z) × 100 · length table under 24 months, height table from 24 months
The WHO Child Growth Standards give the median (M) and coefficient of variation (S) of length or height for every month from birth to 5 years. Babies under 2 years are measured lying down (recumbent length); from 2 years children are measured standing, which reads about 0.7 cm shorter, so the WHO switches tables at 24 months. A z-score below −2 defines stunting (chronic undernutrition) and below −3 severe stunting — key indicators in Latin American and global child-health programs.
Worked example
A 12-month-old girl who is 76 cm long: the WHO median is 74.0 cm (M = 74.015, S = 0.03479), so z = (76 ÷ 74.015 − 1) ÷ 0.03479 = 0.77, which is percentile 78.0 — a normal height for age, with a normal band of 69.2–78.9 cm.
Sources: WHO Child Growth Standards — Length/height-for-age · WHO (2006) Child Growth Standards: methods and development
Frequently asked questions
How is a baby’s length measured?
Under 2 years, the baby lies flat on a measuring board with the head against the fixed end, legs straightened and feet flat against the movable foot piece. Home tape measurements are less accurate, so expect differences of 1–2 cm from the clinic.
What does the height percentile mean?
A percentile of 78 means that 78 out of 100 healthy children of the same age and sex are shorter. Any percentile between about 3 and 97 is usually normal; the trend over several visits matters more than a single value.
What is stunting?
Stunting means a length or height-for-age more than 2 standard deviations below the WHO median. It reflects long-term undernutrition or repeated illness and is linked to poorer development, so it should be assessed by a health professional.
Why does the result change at 24 months?
At 2 years the WHO switches from lying length to standing height. Standing height is about 0.7 cm shorter for the same child, so the median for height at 24 months is lower than the median for length.
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This calculator gives general guidance and is not a diagnosis or medical advice. If you are worried about your child, or they seem unwell, contact your pediatrician, a health center or emergency services.