Birth Weight Percentile Calculator

Your details

Sex affects the reference percentile curves; male infants are on average slightly heavier.
Complete weeks of gestation at delivery (23 to 41).
weeks
Extra days beyond the complete weeks (0 to 6).
days
Birth weight measured in grams.
g
PercentileAppropriate for GA (AGA)
36

Percentage of same-sex, same-gestational-age babies lighter than this weight

Z-score-0.36
Birth weight3400 g
Growth categoryAppropriate for Gestational Age (AGA)
Weight categoryNormal Birth Weight (NBW)
10th percentile for this GA2950 g
Median (50th) for this GA3579 g
90th percentile for this GA4233 g
36 th percentile28.7% below · Percentile

36.0th percentile - Appropriate for Gestational Age (AGA)

  • A percentile between 10 and 90 is the normal range (Appropriate for Gestational Age). The baby's weight is in the expected range for 40 weeks gestation.
  • The median birth weight for a boy at 40 weeks is about 3579 g. The SGA threshold is 2950 g and the LGA threshold is 4233 g.
  • Percentile is a population comparison, not a direct measure of health. Growth trend over multiple measurements matters more than any single reading.

Next stepShare this result with your pediatrician or neonatologist. A single birth weight percentile is one piece of clinical information; complete assessment includes gestational age accuracy, maternal history, and postnatal growth trajectory.

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