How Old Is My Baby in Months?

Development during infancy and early toddlerhood changes dramatically from month to month. Using months gives clinicians the precision needed to accurately assess milestones, growth percentiles, and vaccine schedules. The practice typically continues until around age 2–3.

One year old is 12 months. Two years old is 24 months. Eighteen months is 1 year and 6 months. Use this calculator to get the exact total for any date of birth.

Actual (chronological) age counts from the birth date. Corrected age adjusts for prematurity by subtracting the weeks born early. For example, a baby born 8 weeks early at 5 months chronological age has a corrected age of about 3 months. Most pediatricians use corrected age for milestones until age 2.

Most babies take their first independent steps between 9 and 12 months, with the typical range extending to 15 months. If a child is not walking by 18 months, a developmental evaluation is usually recommended.

Yes. 30 months = 2 years and 6 months = 2.5 years. This calculator shows all three representations so you always have the number pediatricians prefer (months) alongside the more intuitive years-and-months format.