Adjusted Age Calculator for Premature Babies

Babies born early reach milestones by their adjusted age (also called corrected age), not their age since birth. Enter the birth date and the due date – or the week of pregnancy at birth – to find it.

What is adjusted (corrected) age?

Adjusted age is your baby’s age since birth minus the number of weeks they were born early. A full-term pregnancy is counted as 40 weeks.

Formula: adjusted age = actual age − (40 weeks − weeks of pregnancy at birth)

Example: a baby born at 32 weeks is 8 weeks early. At 6 months old (26 weeks), the adjusted age is 26 − 8 = 18 weeks, about 4 months.

Why adjusted age matters

Doctors and therapists compare a premature baby’s development – smiling, rolling, sitting, talking – with their adjusted age. A baby born 2 months early who is 6 months old usually does what a 4-month-old does, and that is completely normal.

How long should you use adjusted age?

Most pediatricians use adjusted age for growth and development checks until about age 2, and sometimes until 3 for babies born very early. Vaccinations, however, follow the actual age since birth.

Frequently asked questions

What if I only know the weeks of pregnancy?

Leave the due date empty and enter the week of pregnancy at birth, for example 32. The calculator uses 40 weeks as full term.

Is this medical advice?

No. It is a calculation tool. Talk to your pediatrician about your baby’s development.