Pediatrics
Baby Weight Percentile Chart (WHO) — Is My Baby Normal?
Understand if your child's weight is appropriate for their age and how to spot growth issues early.
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Weight percentile
What does the weight percentile tell you?
The weight percentile compares your child to a reference group of 100 healthy children of the same age and sex. If your child is at the 75th percentile, it means they weigh more than 75% of children in the reference group and less than the remaining 25%. This ranking is derived from the WHO Child Growth Standards (2006), which were based on data from approximately 8,500 breastfed children across six countries (Brazil, Ghana, India, Norway, Oman, and the United States) raised under optimal health conditions.
A common misconception is that the 50th percentile is the 'ideal.' It is simply the midpoint. A child tracking steadily at the 20th percentile can be just as healthy as one tracking at the 80th. What matters far more than a single number is the consistency of the child's growth pattern over time.
Understanding the reference ranges
WHO weight-for-age categories
3rd - 97th percentile
Normal range
The vast majority of healthy children fall within this band. A child anywhere in this range is generally considered appropriately nourished, provided they are tracking consistently along their own curve.
Below 3rd percentile
Underweight
May indicate inadequate caloric intake, malabsorption (e.g., celiac disease, cow's milk protein allergy), chronic illness, or a genetic variant. Requires evaluation by a pediatrician.
Above 97th percentile
High weight for age
May indicate overfeeding, rapid weight gain, or in rare cases an endocrine condition. Should be assessed in context with the child's height and family build.
Below 1st percentile
Severe underweight
Urgent medical assessment is recommended to rule out failure to thrive, neglect, or serious underlying conditions.
Why the growth curve matters more than today's number
A single weight measurement is a snapshot. It can be influenced by a recent meal, hydration status, clothing, or the time of day. The real clinical value of weight percentiles comes from plotting multiple measurements over time to create a growth curve.
Pediatricians look for children who stay within the same growth channel, meaning their percentile remains roughly stable from visit to visit. A child who has always been at the 25th percentile and continues to track along that line is growing normally. In contrast, a child who drops from the 50th to the 10th percentile over six months is showing a worrisome trend, even though both numbers fall within the 'normal' range.
According to the National Institute for Health and Care Excellence (NICE) guidelines, a drop of two or more major percentile channels is defined as faltering growth and warrants clinical investigation. Similarly, rapid upward crossing of two channels may indicate excessive weight gain relative to height.
Normal weight gain patterns by age
Understanding typical weight gain rates helps parents calibrate expectations:
Expected weight gain
0-3 months
150-200 g/week
Rapid early growth. Breastfed babies may gain slightly less than formula-fed babies after the first month.
3-6 months
100-150 g/week
Growth velocity begins to slow. Doubling of birth weight typically occurs by 4-5 months.
6-12 months
70-100 g/week
Further deceleration. Tripling of birth weight is expected by 12 months.
1-2 years
40-60 g/week
Toddlers often become more selective eaters, and growth slows. Weight gain of about 2-3 kg total in the second year is normal.
2-5 years
~2 kg/year
Steady, slow gain. Children naturally lean out during this period as they become more active.
Common reasons for percentile shifts
Benign causes
- Catch-up or catch-down growth in the first 18 months as the baby adjusts from birth size to genetic potential.
- Illness-related dips: A week of gastroenteritis can cause a temporary weight drop that resolves within a few weeks.
- Feeding transitions: Switching from breast milk to formula or from formula to solid foods may briefly alter the growth pattern.
- Growth spurts: Babies often gain weight in bursts rather than at a perfectly steady rate.
Causes that need investigation
- Persistent downward crossing of two or more percentile channels over several months.
- Weight loss after the newborn period (beyond the normal 5-10% loss in the first few days of life).
- Weight very disproportionate to height (e.g., weight at the 5th percentile but height at the 75th), which may indicate undernutrition.
- Excessive weight gain relative to height, which may signal overfeeding or an underlying endocrine issue.
- Feeding difficulties: recurrent vomiting, refusal to eat, or pain with feeding may point to reflux, food allergy, or mechanical issues.
How to weigh your child accurately
- Use the same scale each time, ideally a calibrated infant scale for babies under 2.
- Weigh without clothes and a clean diaper (or no diaper for infants).
- Measure at roughly the same time of day, preferably before a feed.
- Record the weight to the nearest 10 grams for infants and 100 grams for older children.
- Avoid comparing your child's weight to other children informally. Growth charts use standardized populations for a reason.
Using the weight percentile calculator
Our calculator uses the WHO Child Growth Standards to return your child's exact weight-for-age percentile and z-score. Enter the child's sex, date of birth (or exact age in months), and current weight. The tool will display where your child falls on the growth curve and flag whether the value is within the normal range, below the 3rd percentile, or above the 97th.
For the best results, track at least three data points over several months. A single reading provides a snapshot, but three or more readings reveal a trend. Bring the results to your pediatrician to discuss in the context of feeding history, developmental milestones, and family growth patterns.
When to consult a pediatrician
See your doctor if:
There is objective weight loss after the newborn period; the growth curve flattens or drops for several consecutive months; weight is very disproportionate to height; the child shows signs of dehydration, lethargy, or persistent feeding refusal; or you have any gut feeling that something is off. Parents' intuition, combined with objective data, is a powerful diagnostic tool.
This article is for educational purposes only and does not replace professional medical advice. If you are concerned about your child's weight, consult a pediatrician or pediatric nutrition specialist for an individualized assessment.
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