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Baby Age Calculator
Find out exactly how old your baby is in weeks, months, and days. Perfect for tracking milestones, doctor visits, and those "how old is your baby?" questions.
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Frequently Asked Questions
Doctors use weeks because infant development happens rapidly. A 12-week-old baby is developmentally different from a 3-month-old (which could be anywhere from 12-14 weeks). Weeks provide more precise tracking for vaccinations, feeding schedules, and developmental milestones during the first year.
Since months vary in length (28-31 days), weeks don't convert evenly. Roughly, 4.3 weeks equals one month. Our calculator does the precise math for you, accounting for actual calendar months, so you always know your baby's exact age in both weeks and months.
Most parents switch from weeks to months around 12-16 weeks (3-4 months). After the first year, age is typically given in months until age 2, then in years. However, your pediatrician may continue using weeks for specific medical tracking even after this point.
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