Infant Growth Percentile Calculator
Weight, length and head circumference percentiles for babies 0-24 months.
Enter your values
ⓘ Live results
- Weight percentile
- 53.3th (z = 0.08)
- Length percentile
- 83.1th (z = 0.96, median 64.8 cm)
- Head circumference percentile
- 52.8th (z = 0.07, median 43.4 cm)
- Median weight at this age
- 7.83 kg
- Median length at this age
- 64.8 cm
- Healthy range (3rd-97th)
- 6.21 - 9.45 kg
Working
- 1z = (7.9 - 7.83) / 0.86 = 0.08
Quick answer
Growth percentiles compare a baby with WHO reference data for the same age and sex. A z-score of 0 is the median, and anything between the 3rd and 97th percentile is usually normal.
z = (measure - median) / SD; percentile = normal CDF(z)
How to use the Infant Growth Percentile Calculator
- 1Enter your baby's age in months, using decimals for part months such as 6.5.
- 2Add weight in kilograms and length and head circumference in centimetres.
- 3Look at the trend across visits rather than a single percentile reading.
Worked example
Using the values the calculator loads with:
Inputs
- SexBoy
- Age6 months
- Weight7.9 kg
- Length67 cm
- Head circumference43.5 cm
Results
- Weight percentile53.3th (z = 0.08)
- Length percentile83.1th (z = 0.96, median 64.8 cm)
- Head circumference percentile52.8th (z = 0.07, median 43.4 cm)
- Median weight at this age7.83 kg
- Median length at this age64.8 cm
- Healthy range (3rd-97th)6.21 - 9.45 kg
- z = (7.9 - 7.83) / 0.86 = 0.08
Frequently asked questions
Is a low percentile a problem?
Not on its own. A baby steadily tracking the 10th percentile is usually fine; a baby crossing down through two percentile bands is what prompts a review.
Are these exact WHO tables?
They are close smooth approximations of the WHO 0-24 month standards for quick checks. Your clinic's printed chart remains the reference for medical decisions.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.