Preemie Corrected Age Calculator (Adjusted Age for Premature Babies)

About this tool

This calculator works out a premature baby’s corrected age, also called adjusted age, from the birth date and how many weeks pregnant the mother was at birth. It also shows the age since birth, how early the baby was born and the original due date.

Corrected age is the age since birth minus the number of weeks the baby was born early, counting from 40 weeks. Babies born at 37 weeks or later are full term and need no correction.

Use corrected age to check milestones and growth until about age 2, and use the age since birth for vaccines, which preterm babies get on the regular schedule.

Common questions

How do I calculate my preemie’s corrected age?

Take your baby’s age since birth and subtract how many weeks early they were born (40 weeks minus the weeks of pregnancy at birth). A baby born at 32 weeks who is 6 months old has a corrected age of about 4 months.

Until what age should I use corrected age?

Use corrected age for milestones and growth until about age 2. Most preterm babies have caught up by then.

Do premature babies get vaccines by corrected age?

No. Preterm babies get their vaccines on the regular schedule, using the age since birth.

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