Baby Weight Percentile Calculator
CDC growth charts · 0-24 months
Enter your baby's age, weight, and sex to find their growth percentile.
Weight Percentile
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CDC growth chart
DetailsValue
Baby's Weight—
Age—
Percentile—
Category—
5th percentile (low)—
50th percentile (median)—
95th percentile (high)—
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Understanding Baby Growth Percentiles
A baby's weight percentile shows how their weight compares to other babies of the same age and sex. A 50th percentile means your baby weighs more than 50% of babies the same age. Percentiles ranging from 5th to 95th are all considered normal.
Growth trends matter more than a single measurement. A baby consistently at the 20th percentile is growing normally. A baby who drops from the 60th to the 10th percentile over several months warrants discussion with a pediatrician. Your pediatrician tracks weight, length, and head circumference at every well-baby visit.
What is a Normal Percentile?
All percentiles from 5th to 95th are considered within the normal range by the CDC. There is no 'ideal' percentile — a healthy baby can be at the 10th or the 90th. Below the 5th percentile (underweight) or above the 95th (overweight) warrants monitoring, but doesn't automatically indicate a problem.
Growth Trends vs Single Points
A single percentile measurement is less informative than the trend over time. Consistent growth along any percentile curve indicates healthy development. Crossing two major percentile lines up or down (e.g., dropping from 75th to 25th) in a short period is more concerning than absolute position.
Boys vs Girls
Boys and girls have different growth charts because boys are typically slightly heavier at most ages. Using the correct sex is essential for accurate percentile calculation. The CDC provides separate charts, as does the WHO for the first 2 years.
CDC vs WHO Charts
The CDC recommends using WHO growth charts for children under 2 years old in the US (updated 2010 guidance), and CDC charts for ages 2-20. WHO charts are based on children raised under optimal conditions (breastfed, non-smoking household), representing ideal growth rather than national average. This calculator uses CDC reference data.
This calculator uses CDC reference data for informational purposes only. Growth assessment requires clinical evaluation by a qualified healthcare provider. Always discuss your baby's growth with your pediatrician.
Frequently Asked Questions
What does baby weight percentile mean?+
A percentile tells you how your baby's weight compares to other babies of the same age and sex in the reference population. 50th percentile: your baby weighs more than 50% of babies the same age. 75th: weighs more than 75%. 25th: weighs less than 75% but is still completely normal. All values from 5th to 95th percentile are within the normal healthy range.
What percentile is considered underweight for a baby?+
Below the 5th percentile for weight-for-age may indicate underweight, but context matters enormously. A baby consistently at the 3rd percentile who is alert, feeding well, hitting milestones, and trending along their curve may be perfectly healthy (small parents often have small babies). 'Failure to thrive' is diagnosed based on dropping across percentile lines and clinical assessment, not a single number.
How often should I track my baby's weight?+
Pediatricians track weight at every well-baby visit: 3-5 days (newborn check), 1 month, 2 months, 4 months, 6 months, 9 months, 12 months, 15 months, 18 months, 2 years, then annually. Between visits, weight tracking at home is helpful but not necessary if the baby is feeding well, producing wet diapers, and meeting developmental milestones.
Why did my baby drop percentiles?+
Some percentile drop is normal and expected. Many babies are born at a higher-than-genetic percentile due to gestational factors, then drop to their genetic 'true' percentile in the first 3-6 months. Breastfed babies often grow faster than formula-fed in the first 3 months, then slower. If your baby drops significantly (crossing two major percentile lines) without explanation, discuss with your pediatrician.
What is the average baby weight at 2 months?+
Average weight at 2 months (50th percentile): Boys ~5.6 kg (12.3 lbs). Girls ~5.1 kg (11.2 lbs). Normal range (5th-95th percentile): Boys 4.3-7.1 kg (9.5-15.7 lbs). Girls 3.9-6.6 kg (8.6-14.5 lbs). Babies typically regain birth weight by 10-14 days and gain about 150-200g (5-7 oz) per week in the first 3 months.
How much weight should a newborn gain per week?+
Expected weight gain: Birth to 3 months: 150-200g (5-7 oz) per week. 3-6 months: 100-150g (3-5 oz) per week. 6-12 months: 70-90g (2-3 oz) per week. Most babies lose 5-10% of birth weight in the first week (normal), regain it by days 10-14, then gain steadily. Breastfed babies may be slightly slower gainers in months 4-12 compared to formula-fed.
What is the average birth weight?+
Average US birth weight: Boys ~3.4 kg (7.5 lbs). Girls ~3.3 kg (7.3 lbs). 50th percentile at birth. Low birth weight is defined as under 2.5 kg (5.5 lbs). Macrosomia (large baby) is typically over 4.0 kg (8.8 lbs). Factors affecting birth weight: gestational age, maternal nutrition, maternal weight and height, multiple gestation, genetic factors.
When should I worry about baby weight?+
Discuss with your pediatrician if: baby doesn't regain birth weight by 2 weeks, baby loses more than 10% of birth weight, drops more than two major percentile lines, appears lethargic or unresponsive, is not producing 6+ wet diapers per day after day 5, shows signs of jaundice worsening. These may indicate feeding difficulties, metabolic issues, or other conditions that need assessment.
Do formula-fed and breastfed babies grow differently?+
Yes. Breastfed babies typically gain weight faster than formula-fed in the first 3 months (due to caloric density differences), then slower from 3-12 months. By 12 months, the difference is minimal. WHO growth charts were developed from breastfed babies under optimal conditions, so breastfed babies may appear to 'underperform' on CDC charts in months 6-12 — this is not a clinical problem.
What is a healthy weight for a 1-year-old?+
Average weight at 12 months (50th percentile): Boys ~9.6 kg (21.2 lbs). Girls ~8.9 kg (19.6 lbs). Most babies triple their birth weight by 12 months. Normal range (5th-95th percentile): Boys 7.7-11.8 kg. Girls 7.1-11.0 kg. Length at 12 months averages about 74-76 cm (29-30 inches). Head circumference: boys ~46 cm, girls ~45 cm.