Newborn length chart by week
WHO length percentiles for newborn girls and boys at every week from birth to 13 weeks, in cm with inches for the median. For older babies, see the baby length chart by month.
Key numbers
- At birth, the WHO median length is 49.1 cm (19.3 in) for girls and 49.9 cm (19.6 in) for boys.
- At 6 weeks, the median is 55.1 cm (21.7 in) for girls and 56.2 cm (22.1 in) for boys.
- At 13 weeks (about 3 months), the median is 59.8 cm (23.5 in) for girls and 61.4 cm (24.2 in) for boys.
- In the first 13 weeks median length grows about 10.6 cm for girls and 11.5 cm for boys, close to a centimeter a week.
Girls: length by week (WHO)
Values in cm at each percentile. Median also in inches.
| Age | 3th | 15th | Median | 85th | 97th | Median (in) |
|---|---|---|---|---|---|---|
| Birth | 45.6 | 47.2 | 49.1 | 51.1 | 52.7 | 19.3 |
| 1 week | 46.8 | 48.4 | 50.3 | 52.3 | 53.9 | 19.8 |
| 2 weeks | 47.9 | 49.5 | 51.5 | 53.5 | 55.1 | 20.3 |
| 3 weeks | 48.8 | 50.5 | 52.5 | 54.5 | 56.1 | 20.7 |
| 4 weeks | 49.7 | 51.4 | 53.4 | 55.4 | 57.0 | 21.0 |
| 5 weeks | 50.5 | 52.2 | 54.2 | 56.3 | 57.9 | 21.4 |
| 6 weeks | 51.3 | 53.0 | 55.1 | 57.1 | 58.8 | 21.7 |
| 7 weeks | 52.1 | 53.8 | 55.8 | 57.9 | 59.6 | 22.0 |
| 8 weeks | 52.8 | 54.5 | 56.6 | 58.7 | 60.4 | 22.3 |
| 9 weeks | 53.4 | 55.2 | 57.3 | 59.4 | 61.1 | 22.5 |
| 10 weeks | 54.1 | 55.8 | 57.9 | 60.1 | 61.8 | 22.8 |
| 11 weeks | 54.7 | 56.4 | 58.6 | 60.7 | 62.5 | 23.1 |
| 12 weeks | 55.3 | 57.0 | 59.2 | 61.4 | 63.1 | 23.3 |
| 13 weeks | 55.8 | 57.6 | 59.8 | 62.0 | 63.7 | 23.5 |
Boys: length by week (WHO)
Values in cm at each percentile. Median also in inches.
| Age | 3th | 15th | Median | 85th | 97th | Median (in) |
|---|---|---|---|---|---|---|
| Birth | 46.3 | 47.9 | 49.9 | 51.8 | 53.4 | 19.6 |
| 1 week | 47.5 | 49.1 | 51.1 | 53.1 | 54.7 | 20.1 |
| 2 weeks | 48.8 | 50.4 | 52.3 | 54.3 | 55.9 | 20.6 |
| 3 weeks | 49.8 | 51.4 | 53.4 | 55.4 | 57.0 | 21.0 |
| 4 weeks | 50.7 | 52.4 | 54.4 | 56.4 | 58.0 | 21.4 |
| 5 weeks | 51.7 | 53.3 | 55.3 | 57.4 | 59.0 | 21.8 |
| 6 weeks | 52.5 | 54.2 | 56.2 | 58.3 | 59.9 | 22.1 |
| 7 weeks | 53.4 | 55.0 | 57.1 | 59.1 | 60.8 | 22.5 |
| 8 weeks | 54.1 | 55.8 | 57.9 | 60.0 | 61.6 | 22.8 |
| 9 weeks | 54.9 | 56.6 | 58.7 | 60.7 | 62.4 | 23.1 |
| 10 weeks | 55.6 | 57.3 | 59.4 | 61.5 | 63.2 | 23.4 |
| 11 weeks | 56.3 | 58.0 | 60.1 | 62.2 | 63.9 | 23.7 |
| 12 weeks | 56.9 | 58.7 | 60.8 | 62.9 | 64.6 | 23.9 |
| 13 weeks | 57.6 | 59.3 | 61.4 | 63.5 | 65.2 | 24.2 |
Reading a newborn’s length
Babies grow longer fastest in the first weeks: close to a centimeter a week, slowing to about half that by 6 months. Length is also the hardest measurement to take, because newborns curl up and resist having their legs straightened.
Small jumps between visits are usually measurement noise. What matters is the trend over several checkups: a baby who stays near the same percentile is growing as expected, while one whose length falls across two percentile lines, especially if weight does too, is worth raising with your pediatrician. More in What percentile should my baby be?
Check a length measurement
Enter a date of birth and at least one measurement to see the percentile.
Common questions
What is a normal length for a newborn?
On the WHO standard, the 3rd to 97th percentile at birth runs from about 45.6 to 52.7 cm for girls and 46.3 to 53.4 cm for boys.
Why does my baby’s length change between measurements?
Newborns curl up and resist having their legs straightened, so length is the hardest measurement to take. Differences of 1 to 2 cm between two measurements are common and usually reflect the measuring, not growth.
How is a baby’s length measured?
Lying flat on the back, with the head against a fixed board and the legs gently straightened, from the top of the head to the bottom of the heels. Under age 2 children are measured lying down; after that, standing height is used.
When should I talk to the pediatrician?
If length is far outside the chart (roughly below the 2nd or above the 98th percentile), or if length stops increasing or drops across two percentile lines over several visits. Doctors read length together with weight and the parents’ heights.
Track length over time
Growthling plots each length measurement on the WHO chart with its percentile, next to weight and head circumference. Free to sign up.
Start tracking freeSource: WHO Child Growth Standards, length-for-age expanded tables. Related: newborn weight chart by week. For information only; not medical advice.