Average Baby Length by Month: WHO Chart for Girls and Boys

Educational content only, not medical advice. Always talk to your doctor or health visitor about your child.

Average length by month for girls and boys

WHO median length by age
Age	Girls	Boys
Birth	49.1 cm 19.3 in	49.9 cm 19.6 in
1 month	53.6 cm 21.1 in	54.7 cm 21.5 in
2 months	57.1 cm 22.5 in	58.4 cm 23.0 in
3 months	59.8 cm 23.5 in	61.4 cm 24.2 in
4 months	62.1 cm 24.5 in	63.9 cm 25.2 in
5 months	64.0 cm 25.2 in	65.9 cm 25.9 in
6 months	65.8 cm 25.9 in	67.6 cm 26.6 in
7 months	67.3 cm 26.5 in	69.2 cm 27.2 in
8 months	68.8 cm 27.1 in	70.6 cm 27.8 in
9 months	70.1 cm 27.6 in	72.0 cm 28.3 in
10 months	71.5 cm 28.1 in	73.3 cm 28.8 in
11 months	72.8 cm 28.7 in	74.5 cm 29.3 in
12 months	74.0 cm 29.1 in	75.7 cm 29.8 in
15 months	77.5 cm 30.5 in	79.2 cm 31.2 in
18 months	80.7 cm 31.8 in	82.3 cm 32.4 in
21 months	83.7 cm 32.9 in	85.1 cm 33.5 in
2 years	86.4 cm 34.0 in	87.8 cm 34.6 in
2 years 6 months	90.7 cm 35.7 in	91.9 cm 36.2 in
3 years	95.1 cm 37.4 in	96.1 cm 37.8 in
4 years	102.7 cm 40.4 in	103.3 cm 40.7 in
5 years	109.4 cm 43.1 in	110.0 cm 43.3 in

These are the middle values. Healthy babies sit anywhere between the 3rd and 97th percentile. For the full range see the charts:

How fast do babies grow in length?

Length grows fastest in the first months and slows after the first birthday. Before 2 years babies are measured lying down; after 2 they are measured standing, which reads slightly less.

Frequently asked questions

What is the average baby length at 6 months?

About 65.8 cm for girls and 67.6 cm for boys, the WHO 50th percentile.

Is it a problem if my baby is below average?

No. Average means the middle of a healthy range. Half of all healthy babies are below it. What matters is a steady curve over time, which your doctor checks at each visit.

Where do these numbers come from?

They are the median (50th percentile) values from the WHO Child Growth Standards, built from healthy breastfed babies in six countries.