Baby height percentile calculator
Length-for-age (under 2) and height-for-age (2 to 5) percentiles on the WHO growth standards, in centimetres or inches.
WHO is what US paediatricians use under 2. For premature babies, percentiles use corrected age until 2 years.
Enter length / height to see the percentile and where it sits on the WHO curves.
What a percentile actually means
Imagine 100 healthy, breastfed six-month-old girls from the WHO study, lined up from lightest to heaviest. A baby "on the 30th percentile" is heavier than about 30 of them and lighter than about 70. Drag to pick a baby.
- The 50th isn't the "goal". The 10th and the 90th percentile are both perfectly healthy positions. Half of all healthy babies are below the median.
- Percentiles squash at the edges. Moving from the 50th to the 84th takes one standard deviation (0.95 kg here); moving from the 97th to the 99th takes much less than that. So a jump between high percentiles can mean a few grams.
- The curve matters more than the dot. Paediatricians watch whether a baby follows roughly the same line over time. Crossing two major centile lines downwards is what prompts a closer look.
Average baby length by month (WHO median)
| Age | Boys | Girls |
|---|---|---|
| Birth | 49.9 cm | 49.1 cm |
| 1 mo | 54.7 cm | 53.6 cm |
| 2 mo | 58.4 cm | 57.1 cm |
| 3 mo | 61.4 cm | 59.8 cm |
| 4 mo | 63.9 cm | 62.1 cm |
| 6 mo | 67.6 cm | 65.7 cm |
| 9 mo | 72.0 cm | 70.1 cm |
| 12 mo | 75.7 cm | 74.0 cm |
| 18 mo | 82.3 cm | 80.7 cm |
| 2 yrs | 87.1 cm | 85.7 cm |
For a guess at adult height, see the child height predictor.
Frequently asked questions
How much do babies grow in length?
About 25 cm (10 in) in the first year, which is roughly half their birth length, then around 12 cm in the second year and 6–8 cm a year after that.
Is length the same as height?
The WHO standards use recumbent length (lying down) under 2 years and standing height from 2 years. Standing height is on average 0.7 cm shorter, and the WHO tables already account for that switch.
Does a tall baby become a tall adult?
Only loosely. Length in the first months reflects conditions in the womb more than genetics. By about age 2, height percentile becomes a much better predictor, which is why height predictors use 2-year height. Try our child height predictor.
Data: WHO Child Growth Standards (2006) LMS tables, birth to 5 years; CDC 2000 growth charts LMS tables (cdc.gov/growthcharts), birth to 20 years. Percentiles are computed with the LMS method: z = ((X/M)^L − 1) / (L·S). The CDC recommends the WHO standards for all US children under 2.