Free tool
Work out a premature baby's corrected age from birth date and weeks of gestation, shown beside chronological age.
Enter the date of birth, the test date, and the weeks of pregnancy at birth.
Years;months format, e.g. 4;7 is 4 years 7 months. Days borrow from the actual previous month; some test manuals borrow 30 days or round days differently, so follow your test's own rules for scoring.
Subtract the weeks born early from chronological age, or count from the due date.
Subtract the gestational age at birth from 40 weeks to get the weeks born early, then take that many weeks off the chronological age. By hand, the simplest route is to find the due date by adding those weeks to the birth date, then count from the due date.
A baby born 8 weeks early is 6 months 10 days old, and 4 months 13 days corrected.
A fictional baby, N., was born on 10 January 2026 at 32 weeks, so 8 weeks early. The due date was 7 March 2026. On 20 July 2026, N.'s chronological age is 6 months and 10 days, and the corrected age is 4 months and 13 days. Record both, with the gestational age at birth beside them.
Chronological age is the official age. Corrected age is for development and test manuals.
Chronological age is used for birthdays, school and most records. Corrected age is used when looking at development or choosing the right tables in a test manual. Many clinicians correct for children born before 37 weeks until about 24 months of chronological age. Some manuals set a different rule.
Follow your test's instructions and your clinic's practice, and state in your report which age you used and why.
It is a date calculation only. It says nothing about whether development is on track.
Corrected age does not say whether a baby's development is on track and does not predict anything. Questions about how a baby is growing, feeding, moving or communicating belong with the baby's paediatrician or therapy team.
Hearing two ages is normal. Bring the birth date and weeks of gestation to appointments.
If your baby was born early, you may hear both ages at follow-up visits. The date of birth and weeks of gestation are on the hospital discharge papers. If you are unsure which age a professional is using, ask them. Take any questions about your baby to their doctor.
Yes. Dates and weeks stay in your browser and are not saved.
Dates and weeks entered here are used only in your browser and are not sent to healhab or saved after you leave the page.
Corrected age, also called adjusted age, is a premature baby's age counted from the date they were due rather than the date they were born. Subtract the weeks born early (40 minus the weeks of gestation at birth) from chronological age. Enter the date of birth, the date you need and the weeks of gestation above to see both ages.
A baby born eight weeks early has had eight fewer weeks of growing before birth. Corrected age accounts for that when therapists, doctors and parents talk about a young child's age.
Therapists use it to get the age a test manual asks for. Parents use it to understand why their child's team mentions two ages.
Yes. Both terms mean age counted from the due date instead of the birth date. Corrected age is more common in India and the UK.
Babies born before 37 weeks of gestation. The calculator applies correction only when the weeks entered are below 37.
Many test manuals and clinicians correct until about 24 months of chronological age. Follow the manual you are using and your clinic's practice, since some set a different rule.
Yes. The weeks field accepts half weeks between 22 and 44, and the calculator adjusts by the exact number of weeks born early.
No. It is only a way of counting age that accounts for an early birth. Ask your baby's doctor or therapist about development.
School admission uses the date of birth on official documents. Corrected age is for clinical and developmental purposes only.
Keep these as your clinic's own templates, write from reviewed session notes, publish branded PDFs, and keep families updated.
