Adjusted Age Calculator
Find a premature baby's corrected age, adjusted for weeks born early.
PregnancyScience-backed formula
Enter your details
Fill in the fields, then calculate
Please choose a date.
Enter weeks at birth.
Please choose a date.
Awaiting Data
Enter your details and tap Calculate to see your results appear here.
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ResultYour result appears here.
What it measures
Babies born early are often tracked by corrected age, which subtracts the weeks of prematurity. It gives a fairer view of development against full-term milestones.
Key dates line up into an easy week by week timeline.
Corrected age is usually used until about age two.
How to use this calculator
- Enter the baby's birth date.
- Enter gestational age at birth in weeks.
- Optionally set an as-of date.
- Tap Calculate for actual and corrected age.
The formula used
Weeks early = 40 − gestational weeks
Corrected age = actual age − weeks early
Corrected age = actual age − weeks early
- gestational weeks
- Weeks of pregnancy at birth.
- actual age
- Time since birth.
Understanding Your Results
Actual age
Since birth
The calendar age.
Weeks early
40 minus gestation
The adjustment.
Corrected age
Adjusted figure
Compare to full-term babies.
Tips to Improve
- Use corrected age for milestones to about age 2.
- Share both ages with your pediatrician.
- Track growth on corrected-age charts.
- Ask your care team any questions.
Frequently Asked Questions
It compares a preemie's development fairly against full-term peers.
Commonly until around two years of age.
No. Discuss development with your pediatrician.
Scientific References
- American Academy of Pediatrics. (2004). Age terminology during the perinatal period. Pediatrics, 114(5), 1362–1364.
- Wilson-Costello, D., et al. (2007). Corrected age in preterm follow-up. Pediatrics, 119(1).