Baby Growth Percentile Tracker (0–5 yrs): WHO Charts

How Does a Baby Growth Percentile Work?

A growth percentile tells you how your child compares with other healthy children of the same age and sex. If your baby is at the 60th percentile for weight, it means roughly 60% of children that age weigh less and 40% weigh more. A percentile is not a grade — the 25th percentile is just as healthy as the 75th. What pediatricians watch for is a child growing steadily along their own curve over time.

This tracker uses the WHO Child Growth Standards (2006) for ages 0–5 years. For each age and sex the WHO publishes three numbers — L (skew), M (median) and S (variation), known as the LMS method — which convert your child's measurement into a z-score (how many standard deviations they sit from the median) and then into a percentile.

How Do I Read My Child's Growth Chart?

Find the age on the horizontal axis (in months).
Find the measurement (weight, length/height, BMI or head circumference) on the vertical axis.
See which percentile curve the point sits closest to — the 3rd, 15th, 50th, 85th or 97th line.
Track the trend. Add measurements over time and watch whether your child stays near their own curve.

Worked Example

Suppose you have a 6-month-old boy who weighs 8 kg and measures 67 cm in length:

Against the WHO median weight for a 6-month-old boy (≈7.93 kg), 8 kg gives a z-score of about +0.08 — almost exactly the 54th percentile.
His length of 67 cm (WHO median ≈67.6 cm) gives a z-score of about −0.29 — around the 36th percentile.
Both numbers are firmly in the healthy range. Notice the weight and length percentiles differ — that is completely normal and not a cause for concern on its own.

WHO Percentile Ranges and What They Mean

Percentile band	Z-score	What it usually means
Below 3rd	Below −2	Below typical range — discuss with your pediatrician
3rd – 15th	−2 to −1	Lower end of normal
15th – 85th	−1 to +1	Middle of the healthy range
85th – 97th	+1 to +2	Upper end of normal
Above 97th	Above +2	Above typical range — discuss with your pediatrician

Percentile bandBelow 3rd

Z-scoreBelow −2

What it usually meansBelow typical range — discuss with your pediatrician

Percentile band3rd – 15th

Z-score−2 to −1

What it usually meansLower end of normal

Percentile band15th – 85th

Z-score−1 to +1

What it usually meansMiddle of the healthy range

Percentile band85th – 97th

Z-score+1 to +2

What it usually meansUpper end of normal

Percentile bandAbove 97th

Z-scoreAbove +2

What it usually meansAbove typical range — discuss with your pediatrician

Roughly 94% of healthy children fall between the 3rd and 97th percentiles. A single reading just outside that band is not a diagnosis — the trend over time matters far more than any one measurement.

Length vs. Height: Why It Matters

For children under 2 years, the WHO standards expect length measured lying down (recumbent). From 2 years onward they expect height measured standing. Lying length runs slightly longer than standing height (about 0.7 cm), so use the method that matches your child's age for the most accurate percentile.

Weight, Height, BMI or Head — Which Should I Track?

Weight-for-age and length/height-for-age are the everyday measures. BMI-for-age (needs both weight and height) helps show whether weight is proportionate to length. Head circumference is tracked routinely from birth to 36 months because rapid brain growth happens in those years. This tracker calculates whichever measures you enter.

Is It Normal to Cross Percentile Lines?

In the first 2–3 years some shifting is normal as a baby settles onto their genetically determined curve, especially after birth and around the time solids begin. What pediatricians watch for is a sustained crossing of two or more major percentile lines in either direction, which is worth a conversation at your next visit.

Frequently Asked Questions

What is a good growth percentile for my baby?

There is no single "best" percentile. Anywhere between the 3rd and 97th percentile is considered healthy, and the 25th is just as normal as the 75th. What matters most is that your child grows steadily along their own curve over time rather than the exact number.

What do baby growth percentiles actually mean?

A percentile compares your child with other healthy children of the same age and sex. If your baby is at the 60th percentile for weight, about 60% of children that age weigh less and 40% weigh more. It is a comparison, not a score.

Is it bad if my baby is in a low percentile?

Not necessarily. A baby steadily tracking along the 10th percentile is usually perfectly healthy. Concern is more about a sustained drop across two or more major percentile lines, or readings below the 3rd percentile, which are worth discussing with your pediatrician.

Should I measure length or height?

Use recumbent length (lying down) for children under 2 years and standing height from 2 years onward, matching the WHO standards. Lying length runs about 0.7 cm longer than standing height, so using the right method keeps the percentile accurate.

How often should I track my child's growth?

Following the typical well-child visit schedule works well: frequently in the first year, then around 15, 18, 24 months and yearly after that. Tracking at each checkup makes the growth trend clear, which is more useful than any single reading.

When should I be concerned about my child's growth?

Consult your pediatrician if measurements are consistently below the 3rd or above the 97th percentile, if the growth curve shifts sharply across percentile lines, or if weight and height percentiles differ greatly from each other.

Methodology and Sources

This tracker implements the WHO Child Growth Standards (0–60 months) for weight-for-age, length/height-for-age, BMI-for-age and head circumference-for-age. Percentiles and z-scores are derived with the WHO LMS method using the official L, M and S parameters for each age and sex. The normal range follows the WHO convention of ±2 standard deviations (about the 2nd to 98th percentile), consistent with American Academy of Pediatrics (AAP) growth monitoring guidance. For children over 5 years, the CDC growth charts (2–20 years) become the standard reference.

Important Considerations

Percentiles are one screening indicator, not a verdict on health. Genetics, prematurity, feeding patterns, illness and overall development all shape a child's growth. This tool provides general guidance based on population standards and cannot replace a professional medical evaluation.

Talk to your pediatrician if a measurement is consistently below the 3rd or above the 97th percentile, if the growth curve shifts sharply across percentile lines, or if you have any concerns about your child's growth or development.

Child Growth Tracker