Baby Length & Height Percentile Calculator
Babies under 2 are measured lying down (length) and older children standing up (height). Enter the measurement and how it was taken to see the length or height-for-age percentile.
Your child
Measurement
Around the widest part: above the eyebrows and ears.
Worked out in your browser. A growth record is kept only in this browser; a share link puts the measurements in the web address.
Age on :
percentile
z-score
:
WHO growth chart
Lines show the 3rd, 15th, 50th (median), 85th and 97th percentiles. The large dot is this measurement; small dots are saved ones.
Growth record
| Date | Age | Weight | Length/height | Head | Actions |
|---|---|---|---|---|---|
No measurements saved yet.
Based on the WHO Child Growth Standards (birth to 5 years), last checked 22 October 2026. Xilfy is not affiliated with WHO. A single measurement says little on its own; how your child grows over several check-ups matters more. This calculator is for information and is not medical advice. If you are worried about your child’s growth, talk to your doctor, nurse, or health visitor.
About the Baby Growth Percentile Calculator
The baby growth calculator shows where your child sits on the WHO growth charts, from birth to 5 years. Enter their weight, length or height, and head circumference to get the percentile and z-score for each, plus weight-for-length and BMI-for-age. It corrects the age of babies born early, works in kg and cm or pounds and inches, and can keep a private growth record in your browser so you can see the curve over time.
How to use it
- 1 Choose boy or girl and enter the date of birth. If your baby was born before 37 weeks, pick the week they were born.
- 2 Enter the date of the measurement and any of weight, length or height, and head circumference.
- 3 Read the percentile for each measurement and what it means, and see the point on the WHO chart.
- 4 Save the measurement to your growth record to plot the next check-up on the same chart, or copy a share link.
Frequently asked questions
What does my baby’s percentile mean?
It compares your baby with 100 healthy babies of the same age and sex. At the 40th percentile for weight, 40 of those babies weigh less and 60 weigh more. A higher or lower percentile is not better or worse; what matters most is that your baby keeps growing along roughly the same curve.
What is a normal percentile for a baby?
Anywhere between the 3rd and 97th percentile is within the usual range. Doctors look more closely below the 3rd or above the 97th, or when a baby drops or climbs across two of the main percentile lines (3rd, 15th, 50th, 85th, 97th) between check-ups.
Which growth charts does this calculator use?
The WHO Child Growth Standards from 2006, for birth to 5 years. They come from healthy, breastfed children in six countries and describe how children should grow in good conditions. The WHO, the CDC (for children under 2), the NHS (as UK-WHO charts), and most countries use them.
Should I use corrected age for a premature baby?
Yes. For a baby born before 37 weeks, doctors use the corrected age, the age counted from the due date, until the second birthday. A baby born at 32 weeks is 8 weeks early, so at 4 months old they are compared with 2-month-old babies. Pick the birth week and the calculator does this for you.
Why does it matter if my child was measured lying down or standing?
Children are a little longer lying down than standing. WHO charts use length (lying) under 2 and height (standing) from 2, so the calculator adds or takes away 0.7 cm if your child was measured the other way.
What is a z-score?
It counts how many standard deviations a measurement is from the median for the age. A z-score of 0 is the 50th percentile, −2 is about the 2nd percentile, and +2 about the 98th. Health workers use z-scores because they stay precise at the extremes.
Is my child’s growth data stored?
No. Everything is worked out in your browser. A saved growth record stays only in this browser on this device, and a share link puts the measurements in the web address.
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