Check your baby's weight percentile using WHO growth charts. Enter age, weight, and sex to see where your child falls.
The WHO weight-for-age growth charts are the gold standard for monitoring infant and child growth worldwide. By comparing your baby's weight to thousands of healthy breastfed children, you can see whether they're growing as expected.
A weight percentile tells you what percentage of children weigh less than your child at the same age. For example, a baby at the 75th percentile weighs more than 75% of babies the same age and sex. Most healthy babies fall between the 5th and 95th percentiles.
This calculator uses simplified WHO weight-for-age median data for boys and girls from birth to 24 months. Enter your baby's age in months, weight, and sex to see their approximate percentile. Always consult your pediatrician for clinical growth assessments. Whether you are a beginner or experienced professional, this free online tool provides instant, reliable results without manual computation. By automating the calculation, you save time and reduce the risk of costly errors in your planning and decision-making process.
Tracking weight percentile helps identify potential growth concerns early. Sudden drops or spikes in percentile may indicate feeding issues, illness, or other conditions. This tool gives a quick estimate between doctor visits so you can monitor trends and have informed conversations with your pediatrician. Having a precise figure at your fingertips empowers better planning and more confident decisions.
Z-score = (Measured Weight − Median Weight for Age/Sex) / Standard Deviation Percentile is derived from the z-score using standard normal distribution. Simplified: percentile ≈ position relative to WHO median ± 1-2 SD bands.
Result: ~55th percentile
A 6-month-old boy weighing 17.5 lbs (7.9 kg) is near the 55th percentile on the WHO weight-for-age chart. This means he weighs more than approximately 55% of boys his age. This is well within the normal range.
Growth percentiles compare your baby to a reference population. The 50th percentile is the median — half of babies weigh more, half weigh less. Being above or below the 50th percentile doesn't mean your baby is overweight or underweight.
Boys and girls follow different growth curves. Boys typically weigh slightly more than girls at the same age. That's why separate charts exist for each sex. Always use the correct chart for your baby.
Watch for sudden percentile drops (falling more than two lines), weight below the 3rd percentile, or weight above the 97th percentile. These may indicate feeding issues, illness, or metabolic conditions. A single reading isn't diagnostic — trends over time are what matter.
Any percentile between the 5th and 95th is considered within normal range. What matters most is that your baby stays on or near their growth curve over time. Every baby has their own healthy percentile.
Not necessarily. Some babies are naturally smaller, especially if parents are petite. Concern arises when a baby drops significantly from their established curve or falls below the 3rd percentile. Always discuss with your pediatrician.
The WHO growth charts are based on healthy breastfed infants from around the world and represent how children should grow under optimal conditions. The CDC charts are based on how US children did grow, which includes formula-fed infants.
Pediatricians typically weigh babies at every well-child visit: 1, 2, 4, 6, 9, and 12 months in the first year. Home tracking once or twice a month is reasonable. Avoid daily weighing, which causes unnecessary stress.
A z-score measures how far your baby's weight is from the median (50th percentile) in standard deviations. A z-score of 0 is exactly average, +1 is about the 84th percentile, and -1 is about the 16th percentile.
No. This provides an estimate based on simplified data. Clinical growth assessments use precise WHO charts, clinical scales, and account for your baby's individual growth pattern. Always rely on your pediatrician for medical decisions.