👶 Baby Percentile Calculator

Calculate your baby's weight, height, and head circumference percentile using WHO growth standards for ages 0–24 months.

Weight Percentile
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th percentile
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📊 Where Your Baby Falls on the Growth Chart

0th25th50th75th100th
Below 3rd — Discuss with doctor 3rd–15th — Monitor 15th–85th — Healthy range 85th–97th — Monitor Above 97th — Discuss with doctor
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Weight Percentile
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Height Percentile
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Head Circ. Percentile

📋 Your Baby's Full Measurements

⚖️ Weight — —
📏 Length / Height — —
📊 WHO Median Weight (50th) —
📊 WHO Median Height (50th) —
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⚕️ Medical Disclaimer: This calculator uses WHO Child Growth Standards (2006) for ages 0–24 months. Percentiles are for educational reference only and are not a substitute for professional medical evaluation. Growth is a trend — one measurement alone is not diagnostic. Always discuss your baby's growth with your paediatrician, who has your baby's full health history and will track multiple measurements over time.

What Is a Baby Growth Percentile?

A growth percentile tells you how your baby's measurements compare to other babies of the same age and sex. If your baby is at the 60th percentile for weight, it means they weigh more than 60% of babies their age — and less than 40%. It is a way of understanding where your baby sits on the spectrum of normal growth, not a grade or score.

Percentiles are calculated using large population reference datasets. This calculator uses the WHO Child Growth Standards, which are based on data from over 8,000 children across six countries and represent how children should grow under optimal conditions.

What Is a Good Percentile for a Baby?

There is no single "best" percentile. A healthy baby can be anywhere from the 5th to the 95th percentile — what matters most is that your baby is following a consistent curve over time, not jumping dramatically between percentiles at each check-up.

Percentile RangeWhat It MeansAction
Below 3rdVery low — possible underweight or growth concernDiscuss with paediatrician
3rd–15thBelow average — may need monitoringMention at next check-up
15th–85thHealthy, normal rangeContinue current routine
85th–97thAbove average — may need monitoringMention at next check-up
Above 97thVery high — possible overgrowth concernDiscuss with paediatrician

Average Baby Weight by Month (0–24 Months)

The following table shows the WHO median (50th percentile) weight for boys and girls. Remember these are averages — a healthy range spans roughly the 15th to 85th percentile.

AgeBoys (50th %ile)Girls (50th %ile)
Birth7.5 lbs / 3.4 kg7.3 lbs / 3.2 kg
1 month9.6 lbs / 4.4 kg8.8 lbs / 4.0 kg
2 months11.5 lbs / 5.2 kg10.6 lbs / 4.8 kg
3 months13.3 lbs / 6.0 kg12.1 lbs / 5.5 kg
4 months14.8 lbs / 6.7 kg13.5 lbs / 6.1 kg
6 months17.2 lbs / 7.8 kg15.8 lbs / 7.2 kg
9 months20.1 lbs / 9.1 kg18.5 lbs / 8.4 kg
12 months22.5 lbs / 10.2 kg20.9 lbs / 9.5 kg
18 months25.8 lbs / 11.7 kg24.5 lbs / 11.1 kg
24 months28.5 lbs / 12.9 kg27.2 lbs / 12.3 kg

Average Baby Height by Month (0–24 Months)

AgeBoys (50th %ile)Girls (50th %ile)
Birth19.7 in / 49.9 cm19.3 in / 49.1 cm
1 month21.2 in / 54.0 cm20.8 in / 52.8 cm
2 months22.8 in / 57.9 cm22.2 in / 56.5 cm
3 months24.0 in / 61.0 cm23.4 in / 59.5 cm
6 months26.6 in / 67.6 cm25.8 in / 65.6 cm
9 months28.3 in / 71.9 cm27.6 in / 70.2 cm
12 months29.9 in / 75.7 cm29.2 in / 74.1 cm
18 months32.3 in / 82.1 cm31.7 in / 80.5 cm
24 months34.5 in / 87.8 cm33.9 in / 86.1 cm

WHO vs CDC Growth Charts — What's the Difference?

Two main growth chart systems are used for babies:

  • WHO Growth Standards (used in this calculator): Based on data from 8,440 healthy breastfed children in six countries (Brazil, Ghana, India, Norway, Oman, USA). These charts represent how children should grow under ideal conditions. Recommended by the AAP for children under 24 months.
  • CDC Growth Charts: Based on a US population sample from 1977–1980. These describe how children did grow in a specific time and place. Used more for children over 2 years old.

Your paediatrician typically uses WHO charts for infants under 2 and CDC charts for children 2 and older.

When Should I Be Concerned About My Baby's Percentile?

A single percentile reading is rarely cause for concern on its own. Your paediatrician is looking for trends over time. Speak with your doctor if:

  • Your baby falls below the 3rd percentile for weight or height
  • Your baby crosses two major percentile lines downward (e.g. drops from 50th to 15th) between visits
  • Weight gain has slowed significantly or stopped for 2+ months
  • Head circumference is not growing month to month (in the first year)
  • Weight is much higher than height percentile (or vice versa) consistently
  • You notice your baby seems unwell, lethargic, or not feeding normally

Frequently Asked Questions

What does the 50th percentile mean for a baby?
The 50th percentile is the median — it means exactly half of babies the same age and sex weigh more, and half weigh less. It is not "average" in the sense of being the only healthy weight. Any percentile between the 15th and 85th is considered within the normal healthy range.
Is a higher percentile better for babies?
No. A baby in the 90th percentile is not healthier than one in the 30th. Percentiles simply show where your baby sits on the growth distribution curve. What matters is consistent growth along their own curve over time, not achieving a particular number.
My baby dropped from the 60th to the 30th percentile — should I worry?
Some shift in percentile is normal, especially in the first 6–12 months as babies settle into their genetic growth pattern. However, a significant drop (crossing two major percentile lines) over a short period is worth discussing with your paediatrician at the next check-up.
Does breastfeeding affect growth percentiles?
Yes, slightly. Breastfed babies tend to gain weight faster in the first 3–4 months and then slow slightly compared to formula-fed babies. The WHO growth charts — which this calculator uses — were specifically developed using breastfed babies as the norm, so they are the most appropriate chart for breastfed infants.
Can premature babies use this calculator?
Premature babies should be assessed using their corrected age (chronological age minus weeks premature) until around 2 years of age. For example, if your baby is 4 months old but was born 8 weeks early, enter 2 months into this calculator. Always consult your paediatrician for premature baby growth tracking.
How accurate is this baby percentile calculator?
This calculator uses the WHO Child Growth Standards LMS parameters (2006), the same reference data used by paediatricians in the US, UK, Canada, and Australia. The accuracy of the result depends on the accuracy of the measurements you enter. Always measure weight on a calibrated scale and length on a flat surface with a proper measuring board for the most reliable results.

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