21 month old baby length (height)
On the WHO growth standard, the average (median) length of a 21-month-old baby boy is 85.1 cm (33.5 in) and of a girl 83.7 cm (32.9 in). The usual range, from the 3rd to the 97th percentile, is 79.7 cm (31.4 in) to 90.6 cm (35.7 in) for boys and 77.9 cm (30.7 in) to 89.5 cm (35.2 in) for girls.
Length percentiles at 21 months (WHO)
The median (50th percentile) is the average length for this age.
| 3th | 15th | Median | 85th | 97th | |
|---|---|---|---|---|---|
| Boys (cm) | 79.7 | 82.1 | 85.1 | 88.2 | 90.6 |
| Boys (in) | 31.4 | 32.3 | 33.5 | 34.7 | 35.7 |
| Girls (cm) | 77.9 | 80.5 | 83.7 | 86.9 | 89.5 |
| Girls (in) | 30.7 | 31.7 | 32.9 | 34.2 | 35.2 |
Check your baby’s length percentile
Enter the exact date of birth for a precise result, or use the inch table below.
Enter a date of birth and at least one measurement to see the percentile.
What percentile is my 21 month old’s length in inches?
WHO percentile for each length at exactly 21 months. A few days older or younger shifts it slightly.
| Length | Boy | Girl |
|---|---|---|
| 30 in (76.2 cm) | below 1st | below 1st |
| 31 in (78.7 cm) | 1st | 6th |
| 32 in (81.3 cm) | 9th | 22nd |
| 33 in (83.8 cm) | 33rd | 52nd |
| 34 in (86.4 cm) | 66th | 81st |
| 35 in (88.9 cm) | 90th | 96th |
| 36 in (91.4 cm) | 98th | above 99th |
Common questions
What is the average length (height) of a 21-month-old baby?
On the WHO growth standard, the average (median) length of a 21-month-old baby boy is 85.1 cm (33.5 in) and of a girl 83.7 cm (32.9 in). The usual range, from the 3rd to the 97th percentile, is 79.7 cm (31.4 in) to 90.6 cm (35.7 in) for boys and 77.9 cm (30.7 in) to 89.5 cm (35.2 in) for girls.
What percentile is 33 inches at 21 months?
On the WHO chart, 33 inches (83.8 cm) at exactly 21 months is about the 33rd percentile for a boy and the 52nd percentile for a girl. The table on this page gives the percentile for every inch in the usual range.
How much does a baby grow around 21 months?
Going by the WHO medians, about 0.9 cm (0.4 in) for boys and 1.0 cm (0.4 in) for girls in the month leading up to 21 months. Single measurements are noisy; a few checkups show the trend better.
Is my 21-month-old short or tall?
A length between the 3rd and the 97th percentile is within the usual range, and much of where a baby sits comes from the parents’ heights. Talk to your pediatrician if length is below the 3rd or above the 97th percentile, or if the curve crosses two of the main percentile lines over a few months.
Also: 21 month old baby weight · baby length chart by month · boys · girls
Source: WHO Child Growth Standards, length/height-for-age, percentiles computed from the WHO LMS tables at 21 completed months. Length is measured lying down until age 2. For information only; not medical advice.