Adjusted Age Calculator
The Adjusted (corrected) Age Calculator works out a premature baby's developmental age by subtracting the months of prematurity from their chronological age. Adjusted age is used to assess growth and milestones more fairly during roughly the first two years. It is an educational tool, not medical advice.
Formula
Adjusted Age = Chronological Age − Months Premature
- Chronological age is the time since the baby was born; months premature is how many months early they arrived (40 weeks minus gestational age at birth).
- Adjusted age = chronological age − months premature.
- Clinicians typically use adjusted age to assess growth and developmental milestones until about 2 years of age.
- This is an educational estimate and does not replace assessment by a paediatrician.
Example Calculation
Inputs
- Chronological Age (months): 18
- Prematurity (months): 2
A baby born 2 months early who is 18 months old chronologically has an adjusted age of 18 − 2 = 16 months.
Frequently asked questions
What is adjusted (corrected) age?
It is a baby's age based on their original due date rather than birth date, found by subtracting the months they were born early from their chronological age.
Why use adjusted age?
Premature babies develop on a timeline closer to their due date, so adjusted age gives a fairer picture of growth and milestones.
Until what age is it used?
Adjusted age is generally used until around 2 years, after which most children catch up and chronological age is used.
How do I find months premature?
Subtract the gestational age at birth from 40 weeks. For example, a baby born at 32 weeks was about 2 months early.
Is this medical advice?
No. It is an educational estimate; always discuss your child's development with a paediatrician.