Baby Age Calculator

During infancy and early childhood, development changes rapidly — sometimes week to week. Measuring in months gives clinicians a much finer resolution to compare milestones, vaccinations, and growth against standardized charts. Pediatricians typically track children in months up until age 2 or 3.

Chronological age is counted from the birth date. Corrected (or adjusted) age accounts for prematurity — you subtract the number of weeks born early from the chronological age. For example, a 4-month-old baby born 8 weeks premature has a corrected age of about 2 months. Corrected age is typically used until age 2–3 for premature babies.

A 1-year-old is 12 months old. At 18 months they are 1 year 6 months. At 2 years they are 24 months. Our calculator gives you the exact months plus leftover weeks and days for any date range.

The American Academy of Pediatrics recommends well-child visits at: 3–5 days (newborn), 1 month, 2 months, 4 months, 6 months, 9 months, 12 months, 15 months, 18 months, 2 years, 2.5 years, 3 years, and annually from age 4 onward. This calculator shows your baby's upcoming checkpoints.

Yes. The 'As of date' field defaults to today but you can change it to any date in the past or future. This is useful for calculating age at a specific event, a doctor's appointment, or a birthday.