Premature Baby Growth Calculator
Enter your gestational age at birth and this calculator automatically adjusts for corrected age — so your preemie's percentile reflects their true developmental stage.
Infant Growth Percentile Calculator.
Enter your baby's measurements and location to see percentiles on the most appropriate growth chart for your region — with interactive curves, growth spurt indicators, and a printable report.
Weight-for-age
Height-for-age
What do these numbers mean?
Multi-child dashboard.
No saved measurements yet
Calculate your baby's percentiles above, then click "Save to Dashboard" to track growth over time.
Open calculatorAll data is stored only in your browser's localStorage. Nothing is sent to any server.
Why corrected age matters
A baby born at 32 weeks has spent 8 fewer weeks developing in the womb than a full-term baby. Comparing them directly to same-age growth charts makes them appear smaller than they actually are for their developmental stage. Corrected age subtracts the weeks of prematurity from the chronological age, so the comparison is fair.
Example
chronological_age = 6 months, born at 32 weeks gestation
weeks_premature = 40 − 32 = 8 weeks
corrected_age = 6 months − (8 ÷ 4.33) weeks ≈ 4.1 months
Clinicians generally use corrected age for growth chart comparisons until a child reaches 24–36 months, by which point most premature babies have caught up to their full-term peers.