Baby Growth Percentile Calculator
Enter your baby's weight or length to see their percentile on the official WHO Child Growth Standards for ages 0 to 24 months. The result shows where your baby sits on the curve and the WHO median for their age.
For reference, the WHO median at this age is 11 lb 5 oz (5.1 kg).
Enter your baby's measurement to see the percentile against the WHO growth standards.
How to read a percentile
Percentiles are a ranking, not a grade. The 85th percentile is not better than the 15th; they are two healthy positions on the same curve. The question your pediatrician asks is not where your baby is but whether they are roughly following their own line over time.
Big jumps across percentile lines, in either direction, are worth a conversation at your next checkup. To see those lines rather than a single number, our baby growth charts draw the same WHO data as curves. So is any reading you take at home that worries you: home scales and squirmy babies are a noisy combination, and clinic measurements settle the question.
Weight by age
The median for each age, with the 3rd to 97th percentile band beneath it, which is the range clinicians treat as typical. Pounds and ounces, with kilograms in brackets.
| Age | Girls | Boys |
|---|---|---|
| Birth | 7 lb 2 oz (3.2 kg)5 lb 6 oz to 9 lb 3 oz | 7 lb 6 oz (3.3 kg)5 lb 8 oz to 9 lb 9 oz |
| 1 mo | 9 lb 4 oz (4.2 kg)7 lb 1 oz to 11 lb 14 oz | 9 lb 14 oz (4.5 kg)7 lb 10 oz to 12 lb 9 oz |
| 2 mo | 11 lb 5 oz (5.1 kg)8 lb 13 oz to 14 lb 6 oz | 12 lb 4 oz (5.6 kg)9 lb 11 oz to 15 lb 7 oz |
| 3 mo | 12 lb 14 oz (5.8 kg)10 lb 2 oz to 16 lb 5 oz | 14 lb 1 oz (6.4 kg)11 lb 4 oz to 17 lb 7 oz |
| 4 mo | 14 lb 3 oz (6.4 kg)11 lb 3 oz to 17 lb 14 oz | 15 lb 7 oz (7.0 kg)12 lb 7 oz to 19 lb 1 oz |
| 5 mo | 15 lb 3 oz (6.9 kg)12 lb 1 oz to 19 lb 3 oz | 16 lb 9 oz (7.5 kg)13 lb 6 oz to 20 lb 5 oz |
| 6 mo | 16 lb 1 oz (7.3 kg)12 lb 13 oz to 20 lb 4 oz | 17 lb 8 oz (7.9 kg)14 lb 3 oz to 21 lb 7 oz |
| 7 mo | 16 lb 14 oz (7.6 kg)13 lb 7 oz to 21 lb 4 oz | 18 lb 5 oz (8.3 kg)14 lb 14 oz to 22 lb 6 oz |
| 8 mo | 17 lb 8 oz (7.9 kg)14 lb to 22 lb 2 oz | 19 lb (8.6 kg)15 lb 7 oz to 23 lb 4 oz |
| 9 mo | 18 lb 2 oz (8.2 kg)14 lb 8 oz to 22 lb 14 oz | 19 lb 10 oz (8.9 kg)15 lb 15 oz to 24 lb 1 oz |
| 10 mo | 18 lb 11 oz (8.5 kg)14 lb 15 oz to 23 lb 10 oz | 20 lb 3 oz (9.2 kg)16 lb 7 oz to 24 lb 12 oz |
| 11 mo | 19 lb 4 oz (8.7 kg)15 lb 5 oz to 24 lb 5 oz | 20 lb 12 oz (9.4 kg)16 lb 14 oz to 25 lb 7 oz |
| 12 mo | 19 lb 12 oz (8.9 kg)15 lb 12 oz to 25 lb | 21 lb 4 oz (9.6 kg)17 lb 5 oz to 26 lb 1 oz |
| 13 mo | 20 lb 3 oz (9.2 kg)16 lb 2 oz to 25 lb 10 oz | 21 lb 12 oz (9.9 kg)17 lb 11 oz to 26 lb 11 oz |
| 14 mo | 20 lb 11 oz (9.4 kg)16 lb 8 oz to 26 lb 4 oz | 22 lb 4 oz (10.1 kg)18 lb 1 oz to 27 lb 5 oz |
| 15 mo | 21 lb 3 oz (9.6 kg)16 lb 14 oz to 26 lb 14 oz | 22 lb 12 oz (10.3 kg)18 lb 7 oz to 27 lb 15 oz |
| 16 mo | 21 lb 10 oz (9.8 kg)17 lb 4 oz to 27 lb 7 oz | 23 lb 3 oz (10.5 kg)18 lb 13 oz to 28 lb 9 oz |
| 17 mo | 22 lb 2 oz (10.0 kg)17 lb 10 oz to 28 lb 1 oz | 23 lb 11 oz (10.7 kg)19 lb 3 oz to 29 lb 2 oz |
| 18 mo | 22 lb 9 oz (10.2 kg)18 lb to 28 lb 10 oz | 24 lb 2 oz (10.9 kg)19 lb 9 oz to 29 lb 11 oz |
| 19 mo | 23 lb (10.4 kg)18 lb 6 oz to 29 lb 4 oz | 24 lb 9 oz (11.1 kg)19 lb 15 oz to 30 lb 5 oz |
| 20 mo | 23 lb 8 oz (10.6 kg)18 lb 12 oz to 29 lb 13 oz | 25 lb (11.3 kg)20 lb 4 oz to 30 lb 14 oz |
| 21 mo | 23 lb 15 oz (10.9 kg)19 lb 2 oz to 30 lb 7 oz | 25 lb 7 oz (11.5 kg)20 lb 10 oz to 31 lb 7 oz |
| 22 mo | 24 lb 6 oz (11.1 kg)19 lb 8 oz to 31 lb | 25 lb 14 oz (11.8 kg)20 lb 15 oz to 32 lb 1 oz |
| 23 mo | 24 lb 13 oz (11.3 kg)19 lb 13 oz to 31 lb 10 oz | 26 lb 6 oz (12.0 kg)21 lb 4 oz to 32 lb 10 oz |
| 24 mo | 25 lb 5 oz (11.5 kg)20 lb 3 oz to 32 lb 3 oz | 26 lb 13 oz (12.2 kg)21 lb 10 oz to 33 lb 4 oz |
Length by age
The median for each age, with the 3rd to 97th percentile band beneath it, which is the range clinicians treat as typical. Inches, with centimeters in brackets.
| Age | Girls | Boys |
|---|---|---|
| Birth | 19.3 in (49.1 cm)18.0 in to 20.7 in | 19.6 in (49.9 cm)18.2 in to 21.0 in |
| 1 mo | 21.1 in (53.7 cm)19.7 in to 22.6 in | 21.5 in (54.7 cm)20.1 in to 23.0 in |
| 2 mo | 22.5 in (57.1 cm)21.0 in to 24.0 in | 23.0 in (58.4 cm)21.5 in to 24.5 in |
| 3 mo | 23.5 in (59.8 cm)22.0 in to 25.1 in | 24.2 in (61.4 cm)22.7 in to 25.7 in |
| 4 mo | 24.4 in (62.1 cm)22.8 in to 26.0 in | 25.2 in (63.9 cm)23.6 in to 26.7 in |
| 5 mo | 25.2 in (64.0 cm)23.6 in to 26.9 in | 25.9 in (65.9 cm)24.4 in to 27.5 in |
| 6 mo | 25.9 in (65.7 cm)24.2 in to 27.6 in | 26.6 in (67.6 cm)25.0 in to 28.2 in |
| 7 mo | 26.5 in (67.3 cm)24.8 in to 28.2 in | 27.2 in (69.2 cm)25.6 in to 28.8 in |
| 8 mo | 27.1 in (68.7 cm)25.3 in to 28.8 in | 27.8 in (70.6 cm)26.2 in to 29.4 in |
| 9 mo | 27.6 in (70.1 cm)25.8 in to 29.4 in | 28.3 in (72.0 cm)26.7 in to 30.0 in |
| 10 mo | 28.1 in (71.5 cm)26.3 in to 30.0 in | 28.9 in (73.3 cm)27.2 in to 30.5 in |
| 11 mo | 28.6 in (72.8 cm)26.8 in to 30.5 in | 29.3 in (74.5 cm)27.6 in to 31.1 in |
| 12 mo | 29.1 in (74.0 cm)27.2 in to 31.0 in | 29.8 in (75.7 cm)28.1 in to 31.6 in |
| 13 mo | 29.6 in (75.2 cm)27.7 in to 31.6 in | 30.3 in (76.9 cm)28.5 in to 32.1 in |
| 14 mo | 30.1 in (76.4 cm)28.1 in to 32.1 in | 30.7 in (78.0 cm)28.9 in to 32.6 in |
| 15 mo | 30.5 in (77.5 cm)28.5 in to 32.5 in | 31.2 in (79.1 cm)29.3 in to 33.0 in |
| 16 mo | 30.9 in (78.6 cm)28.9 in to 33.0 in | 31.6 in (80.2 cm)29.7 in to 33.5 in |
| 17 mo | 31.4 in (79.7 cm)29.3 in to 33.5 in | 32.0 in (81.2 cm)30.0 in to 33.9 in |
| 18 mo | 31.8 in (80.7 cm)29.6 in to 33.9 in | 32.4 in (82.3 cm)30.4 in to 34.4 in |
| 19 mo | 32.2 in (81.7 cm)30.0 in to 34.4 in | 32.8 in (83.2 cm)30.7 in to 34.8 in |
| 20 mo | 32.6 in (82.7 cm)30.3 in to 34.8 in | 33.1 in (84.2 cm)31.1 in to 35.2 in |
| 21 mo | 32.9 in (83.7 cm)30.7 in to 35.2 in | 33.5 in (85.1 cm)31.4 in to 35.6 in |
| 22 mo | 33.3 in (84.6 cm)31.0 in to 35.6 in | 33.9 in (86.0 cm)31.7 in to 36.0 in |
| 23 mo | 33.7 in (85.5 cm)31.3 in to 36.0 in | 34.2 in (86.9 cm)32.0 in to 36.4 in |
| 24 mo | 34.0 in (86.4 cm)31.6 in to 36.4 in | 34.6 in (87.8 cm)32.3 in to 36.8 in |
Frequently asked questions
What does a growth percentile mean?
A percentile compares your baby with other babies of the same age and sex on the WHO growth standards. The 40th percentile for weight means about 40 of 100 babies weigh less and about 60 weigh more. It describes position, not health.
Is a low or high percentile a problem?
Not by itself. Healthy babies live all along the curve, and anywhere between roughly the 3rd and 97th percentile is usually considered within the typical range. What pediatricians watch is the trend: a baby who follows their own curve is generally doing fine.
Which data does this calculator use?
The WHO Child Growth Standards for ages 0 to 24 months, using the official LMS parameters as published by the CDC. These standards describe how healthy breastfed children grow in optimal conditions and are the reference recommended for babies under 2 in most countries.
Why does my pediatrician's number differ slightly?
Clinics may measure differently, use exact ages in days, or use a different reference (some countries switch to CDC charts after age 2). Small differences are normal; the trend across visits matters more than any single reading.
Track the curve, not one number
Growbaby's growth journal keeps every weight and length measurement in one place and shows your baby's own curve over time, alongside milestones, sleep and feeding, so checkup conversations start from real data.
Sources
This tool is for general informational purposes only. It is not a medical device and does not provide medical advice, diagnosis or treatment. Percentiles from home measurements are estimates; clinical decisions belong to your pediatrician with clinical measurements. For any question about your or your baby's health, always consult a qualified healthcare provider.