Global Araç
Baby Weight Percentile
Percentile estimate
Between the 15th and 50th percentile
- 3rd
- 14.1 lbs
- 15th
- 15.7 lbs
- 50th (median)
- 17.4 lbs
- 85th
- 19.4 lbs
- 97th
- 21.4 lbs
Read percentiles as a trend, not a grade
Percentiles measure growth trend over time. A single reading doesn’t mean anything — a healthy baby can sit in the 10th, 50th, or 90th percentile and be perfectly fine. What matters is whether your baby is following their own curve. Track with your pediatrician at each well-visit.
Chart values approximate WHO standards (0–24 months) and CDC references (24–36 months) — useful for a quick check, not a diagnostic tool.
Pediatric growth charts plot weight, height, and head circumference against age and sex to show how a child compares to standard population data. Two main systems: WHO (World Health Organization) charts based on breastfed-baby data from multi-country studies, recommended for ages 0-2 years. CDC charts based on US-population data, recommended for ages 2+ years (and used historically for younger). The 50th percentile means “average — half of babies this age weigh more, half less.” A 75th-percentile baby weighs more than 75% of peers; a 25th-percentile baby weighs less than 75%. Both are normal. Concerning patterns are TRENDS, not single readings: dropping from 75th to 25th percentile across a few months suggests something happening (illness, feeding issue); staying steady at 25th throughout indicates a smaller-than- average but healthy baby on their own consistent curve.
The calculator takes baby age, sex, and current weight (and optionally height / head circumference), then outputs the percentile rank. Useful for: tracking growth between pediatrician visits (most appointments only happen at 1, 2, 4, 6, 9, 12, 15, 18, 24 months for the first two years), spotting a downward trend before the next appointment, comforting parents worried about a baby on a low percentile who's growing consistently. Always discuss findings with your pediatrician; this is informational, not diagnostic.
Critical principles for interpreting percentiles: (1) Trend matters far more than absolute number. A baby at 10th percentile growing along their curve is healthy; a baby dropping from 75th to 50th to 25th over 3 months needs investigation. (2) Both very low (under 5th) and very high (over 95th) deserve attention but neither alone signals a problem — context (parental size, ethnicity, feeding) matters. (3) Birth weight regression — most newborns lose 5-10% body weight in first week (entirely normal); back to birth weight by 2 weeks. Percentile charts handle this phase carefully. (4) Breastfed vs formula- fed — breastfed babies grow rapidly first 3 months then slow; formula-fed grow more steadily. Old growth charts (CDC) used formula-fed data which can flag breastfed babies as “underweight” incorrectly. WHO charts (preferred for under- 2) are based on breastfed babies and avoid this. (5) Premature babies — adjust for gestational age (a 36-week preemie at 3 months chronological age = 2-month-old at full-term equivalent for charting purposes). (6) NEVER compare your baby to a friend's baby. Different babies have different natural curves; comparison creates unnecessary parental anxiety.
Nasıl Kullanılır
- Enter baby's age in weeks or months.
- Pick sex (male / female — different charts).
- Enter weight in lbs / oz or kg.
- Optionally enter height and head circumference.
- Read percentile rank vs age/sex peers.
- Track trend over time at well-child visits.
Ne Zaman Kullanılır
- Tracking baby growth between pediatrician visits.
- Spotting trend changes that warrant earlier appointment.
- Reassuring yourself about a low or high percentile that's consistent.
- Sharing data with telehealth pediatrician for remote consult.
- Curiosity / parental peace of mind.
Ne Zaman Kullanılmaz
- As medical advice — pediatrician visits provide diagnostic context.
- Premature babies without adjusting for gestational age.
- Special-needs / chronic-condition babies — they have individualized growth expectations.
- Comparing your baby to other babies as judgment — every baby is different.
Yaygın Kullanım Senaryoları
- Onboarding a colleague who needs the same calculation/conversion
- Verifying a number or output before passing it on
- Quick use during a typical workday
- Pre-decision sanity-check on inputs and outputs
Sık Sorulan Sorular
What's a normal percentile?
Anywhere from 5th to 95th percentile is considered normal range. Below 5th or above 95th doesn't automatically signal a problem but warrants pediatric attention. The 50th is exactly average — half above, half below. Most babies cluster between 25th and 75th. Consistent percentile (whatever it is) is healthier than fluctuating percentile. Low percentile + thriving baby = small but healthy. Dropping percentile = needs attention.
WHO vs CDC charts — which?
WHO charts for ages 0-24 months. They're based on breastfed-baby data from multi-country studies (Brazil, Ghana, India, Norway, Oman, USA), considered the gold standard for healthy growth in infants. CDC charts for ages 2+ years. They're based on US population data. Most US pediatricians use WHO under 2, CDC after 2. Older CDC charts under-2 used formula-fed data and tended to flag breastfed babies as underweight; WHO fixes this.
Should I worry about low percentile?
Not automatically. A baby at consistent 10th percentile growing along their curve is healthy — just naturally smaller. Concerning: drop in percentile (from 50th to 10th over weeks), failure to gain weight, signs of illness or poor feeding. Talk with pediatrician about TREND, not absolute number. Family history matters — if both parents are small, baby is statistically more likely to be in lower percentiles.
How often should I weigh?
At well-child visits is sufficient for most babies (1, 2, 4, 6, 9, 12, 15, 18, 24 months in the first two years). Daily / weekly home weighing usually creates anxiety without useful info — daily fluctuations dominate signal. Exception: babies with feeding concerns where the pediatrician requests close tracking. For most healthy babies, monthly home checks at most are sufficient between appointments.
What about premature babies?
Adjust for gestational age. A baby born at 36 weeks (4 weeks early) needs “adjusted age” for charting: at 3 months chronological age, use 2-month chart. Most pediatricians adjust for prematurity until age 2 (when developmental catch-up typically completes). This can be confusing for parents — “my 6-month-old is the size of a 4-month-old” reflects gestational adjustment, not failure to thrive.
Can I trust home scales?
Mostly. Bathroom scales (weigh yourself, weigh holding baby, subtract): accurate within 0.5 lb / 200g. Baby scales (digital, $25-100): accurate within 10g — better for tracking small changes. Pediatrician scales are most precise. For trend tracking, consistency matters more than absolute precision — using same scale, same conditions (clothed vs naked, before vs after meals) yields useful trend data even if absolute number is slightly off vs pediatrician.