Baby age calculator
Your baby’s age in months, weeks and days. Born early? Choose the week of pregnancy they were born in, and see their corrected age beside it.
What corrected age is
A baby born early has had less time to grow than a baby born on their due date. Corrected age — sometimes called adjusted age — is their age counted from their due date instead of their birthday.
Six months after birth, a baby born eight weeks early has a corrected age of about four months.
Why it matters
Milestones such as smiling, rolling and sitting, and the growth charts used at checks, are judged against corrected age. Compared with babies born on the same day at full term, a baby born early can seem behind when they are where they should be for their corrected age.
If you are worried about how your baby is developing, talk to your health visitor, nurse or doctor.
Until when
Corrected age is usually used until a baby’s second birthday. After that, their age from birth is used. Your baby’s care team may give you different advice for your baby.
Vaccinations are different: they are given by age from birth, on the usual schedule, however early a baby was born.
Working it out by hand
Take the week of pregnancy your baby was born in away from 40: that is how many weeks early they came. Then take those weeks away from their age.
A baby born at 34 weeks came six weeks early, so at 16 weeks old their corrected age is 10 weeks.
Questions
Is corrected age the same as adjusted age?
Yes. Both mean a baby’s age counted from their due date instead of their date of birth.
My baby was born at 37 weeks. Do they have a corrected age?
No. A baby born at 37 weeks or later is full term, and their age is counted from their date of birth.
Are vaccinations given by corrected age?
No. Vaccinations follow the usual schedule by age from birth, however early a baby was born. Your baby’s nurse, health visitor or doctor will tell you when each one is due.
Is what I enter saved?
Only if you tick “Remember this on this device”, and then only in this browser. Nothing you enter is sent to us.
Sources
- Corrected Age For Preemies — HealthyChildren.org, American Academy of Pediatrics
- Corrected age: premature babies — Raising Children Network
- A quick guide to childhood vaccinations for the parents of premature babies — UK Health Security Agency
Written and checked with AI against the sources below. It is general information, not medical advice.How we make our guidance