Baby Growth Percentile Calculator
Check your baby's weight and height percentile using WHO growth standards
What are Baby Growth Percentiles?
Growth percentiles show how your baby's weight and height compare to other babies of the same age and sex. A baby at the 50th percentile is exactly average — half of all babies the same age weigh more, and half weigh less. A baby at the 75th percentile is heavier than 75 percent of babies their age. Percentiles from the 5th to the 95th are all considered within the normal range.
This calculator uses the World Health Organization (WHO) Child Growth Standards, which are based on data from healthy children raised in optimal conditions across six countries. The WHO charts are recommended for children from birth to age 2 and are the international standard used by paediatricians worldwide.
What if My Baby is Above or Below Average?
A single percentile reading means very little in isolation. What matters most is that your baby follows a consistent growth curve over time. A baby consistently at the 10th percentile is growing normally — they are simply smaller than average. Concern arises when a baby drops significantly across percentile lines between check-ups, which may indicate a feeding or health issue worth discussing with your paediatrician.
Premature babies should have their age adjusted for prematurity. A baby born 8 weeks early and now 4 months old should be plotted at 2 months on the growth chart. Most growth charts and paediatricians automatically adjust for this until the child reaches 2 years of age.
Average Baby Weight and Height by Month
At birth the average baby weighs around 7.5 lbs (3.4 kg) and measures 20 inches (50 cm). By 6 months most babies have doubled their birth weight, typically reaching around 16 lbs (7.3 kg) and 26 inches (66 cm). By 12 months babies have usually tripled their birth weight to around 21 lbs (9.5 kg) and grown to around 30 inches (75 cm). Growth is fastest in the first few months and gradually slows through the first year.
Baby Growth Calculator — Frequently Asked Questions
What do baby growth percentiles mean?
A growth percentile shows how your baby compares to other babies of the same age and sex. A baby at the 50th percentile is exactly average. A baby at the 75th percentile is heavier or taller than 75% of babies the same age. All percentiles from 5th to 95th are considered within the normal healthy range.
What are WHO Child Growth Standards?
WHO Child Growth Standards were developed by the World Health Organization using data from children across six countries raised under optimal conditions. They are used globally as the reference standard for child growth assessment from birth to age 5.
Should I be worried if my baby is in a low percentile?
A single percentile measurement is less important than the trend over time. A healthy baby consistently tracking along any percentile curve is generally not a concern. It is when growth crosses multiple percentile lines upward or downward that a paediatrician assessment may be needed.