Baby Length-for-Age Percentile Calculator

Recumbent length is measured lying flat on a measuring board. Standing height is measured upright. For babies under 2 years, recumbent length is used — it's typically 0.5–1 cm longer than standing height at the same age. WHO charts for 0–24 months are based on recumbent measurements.

Lay your baby on a firm, flat surface. Hold their head straight, stretch their legs gently, and mark the position of the top of the head and the heels. Measure the distance. An infantometer (or two rulers) gives the most accurate result. Home measurements can vary by 1–2 cm — professional measurements at the clinic are more reliable.

Many babies are short simply because their parents are short — genetics account for ~70–80% of adult height. A baby consistently at the 5th or 10th percentile for length but tracking their curve is usually not a concern. What warrants investigation is a baby crossing major percentile lines downward, or falling below the 3rd percentile, especially if weight is also affected.

The median birth length is about 49.9 cm (19.7 inches) for boys and 49.1 cm (19.3 inches) for girls, per WHO data. The normal full-term range is approximately 47–54 cm (18.5–21 inches).

Not necessarily at birth — birth length correlates less strongly with adult height than genes suggest, because birth size is more influenced by the uterine environment. However, by 2 years most babies have settled into the growth channel that reflects their genetic potential.