Adjusted Age Calculator
Determine corrected (adjusted) age for premature infants to interpret growth charts and developmental milestones.
How to Use This Calculator
Confirm important dates
You need the actual birth date, gestational age at delivery, and today's date (or the visit date).
Enter gestational age in weeks and days
For example, 32 weeks + 5 days should be entered as 32 weeks and 5 days.
Review corrected age
Use corrected age for growth charts, developmental screening, and feeding expectations.
Formula
Weeks premature = 40 weeks − (gestational weeks + gestational days ÷ 7).
Adjusted age equals time since the original due date. It is typically used until 24 months of age (32 months for infants born before 30 weeks).
About Adjusted Age
Adjusted (corrected) age accounts for the number of weeks a premature infant was born before 40 weeks gestation. Pediatricians use corrected age to interpret growth percentiles, motor milestones, and feeding expectations.
Why corrected age matters
Most clinicians stop adjusting around 24 months, once many premature infants have caught up in growth and development. Extremely preterm infants may need adjustment a bit longer.
- Ensures fair comparison with babies born at term.
- Prevents over-referral for developmental delays.
- Helps parents set realistic expectations for skills like sitting, crawling, and talking.
Frequently Asked Questions
When should I stop using corrected age?
Most pediatricians stop correcting at 24 months, but for infants born before 30 weeks, continue until 32 months.
Which milestones use corrected age?
Growth charts, motor skills, speech, and feeding expectations all benefit from using corrected age.
Does corrected age affect vaccines?
No. Immunization schedules follow chronological age, not adjusted age.
What if my baby was born at 40 weeks?
The calculator will show zero weeks early, so corrected age equals chronological age.
Can I use this for multiples?
Yes. Twins and triplets often arrive early. Enter each baby's gestational age for individualized corrected ages.