Baby Age and Corrected Age Calculator
See a baby’s age in months, weeks and days, and the corrected age for a baby born early.
Share sends a link that reopens these numbers. Copy details pastes the full breakdown as a list.
The formula
age = as-of date − date of birth corrected age = age − (40 − weeks of gestation at birth) weeks
Corrected age counts from the date the baby was originally due. It applies only to babies born before 37 weeks, and is commonly used up to about age 2.
What to watch out for
Months are calendar months, so a month can be 28 to 31 days. For a baby born before 37 weeks, enter the gestation at birth to see the corrected age alongside the actual age.
Frequently Asked Questions
How do I work out a baby’s age in weeks?
Count the days since birth and divide by 7. From 1 March 2027 to 1 June 2027 is 92 days, which is 13 weeks, 1 day, or 3 months, 0 days.
What is corrected age?
Actual age minus the weeks the baby arrived early, measured against 40 weeks. A baby born at 32 weeks on 1 March 2027 is 3 months, 0 days old on 1 June 2027, with a corrected age of 1 month, 6 days.
How long is corrected age used?
It is commonly used up to about age 2, for babies born before 37 weeks.