Baby · Tracking
Baby Age Calculator
Convert your baby's date of birth into their current age in years, months, weeks and days, and see how close they are to the next milestone — 1 month, 3 months, 6 months, 1 year and beyond.
Last reviewed 24 May 2026
Baby Age Calculator
How to use this calculator
Enter your baby’s date of birth. The calculator returns their current age in three forms — the standard years · months · days format, the total in each unit (total months, weeks, days), and the date of the next paediatric milestone.
Why months matter so much
From birth to age 2, “months old” is the unit paediatricians and developmental specialists use. Vaccination schedules are timed in months. Growth charts run on monthly intervals. Developmental milestones — head control, sitting, first words, first steps — are mapped to month ranges. From age 2 onward the convention shifts to years.
Premature babies — corrected age
If your baby was born preterm, paediatricians track developmental progress using corrected age = chronological age − weeks of prematurity, for roughly the first 2 years. A 6-month-old born 8 weeks early has a corrected age of 4 months — that’s the age to use for milestones. (Vaccinations are usually still timed by chronological age.) This calculator returns chronological age only; adjust manually for prematurity if needed.
Limitations
- Months are calendar months (not 4-week blocks) — different paediatric forms occasionally use 4-week months, which would shift the count slightly.
- Doesn’t handle leap-day birthdays specially — Feb 29 babies show as Feb 28 in non-leap years.