In the early weeks, a lot changes quickly, so many parents and professionals count in weeks. Around three months, most people switch to months, and after two years to years and months.

Corrected age for premature babies

If your baby arrived early, a healthcare professional may use corrected age — actual age minus the weeks they were born early — when talking about development. This calculator shows actual age from the birth date.

How we calculate

We count complete calendar months from the birth date, then the remaining days. Weeks, days and hours are totals since birth, so they won’t add up to the months figure exactly.

FAQ

Questions parents ask

How do I work out my baby’s age in months?

Count the full calendar months since the birth date. A baby born on March 10 is one month old on April 10, two months on May 10, and so on. The calculator does this for you, including remaining days.

Does the calculator store my baby’s details?

No. Everything is calculated in your browser. Nothing you enter is saved or sent anywhere.

What is corrected age?

Corrected age adjusts for premature birth by subtracting the weeks a baby was born before their due date. Ask your healthcare professional whether it applies to your baby.