Baby Age Calculator
Calculate your baby's exact age in years, months, weeks, days, and hours from their birth date. Free baby age calculator with milestone chart showing monthly milestones for the first 24 months.
About This Calculator
The Baby Age Calculator helps parents track their baby's exact age from birth date to any chosen date. Knowing your baby's precise age in months, weeks, and days is essential for monitoring developmental milestones, following vaccination schedules, determining baby formula amounts, and tracking growth percentiles during those critical first two years.
The calculator computes the baby's age using the Gregorian calendar, automatically handling leap years and varying month lengths. The age breakdown shows total years, months, weeks, days, and hours since birth, plus a year-month-day breakdown (e.g., 1 year, 3 months, and 12 days). A milestone calendar displays every monthly milestone from month 1 through month 24, showing the exact date and day of the week for each milestone — useful for planning celebrations and tracking key development checkpoints.
Regional Notes
India: The baby age calculator helps parents track vaccination milestones (6 weeks, 10 weeks, 14 weeks, 9 months, 12 months, 18 months) as recommended by the Indian Academy of Pediatrics (IAP). Many parents also use it to determine the correct baby formula amount per feeding, which varies by age.
United States: The CDC recommends well-baby visits at 1, 2, 4, 6, 9, 12, 15, 18, and 24 months. This calculator helps parents prepare for these appointments by tracking exact age at each visit and monitoring developmental milestones recommended by the American Academy of Pediatrics.
United Kingdom: The NHS recommends health visitor reviews at 6-8 weeks, 9-12 months, and 2-2.5 years. Parents can use this calculator to track when these reviews are due and monitor their baby's growth against the UK-WHO growth charts.
Frequently Asked Questions
How do I use the baby age calculator?
Simply enter your baby's birth date and an optional as-of date (defaults to today). Click calculate to see your baby's exact age in years, months, weeks, days, and hours, plus a milestone calendar showing all monthly milestones for the first 24 months with their corresponding dates and days of the week.
How many months old is my baby?
The calculator shows the total number of months since birth. For example, a baby born on October 10, 2024, will be approximately 9 months old by July 10, 2025. Enter your baby's birth date and today's date to get the exact age in months.
How many weeks old is my baby?
To calculate weeks, multiply the number of months by 4.345. For example, an 11-month-old baby is approximately 4.345 x 11 = 47.8 weeks old. Our calculator does this automatically and shows total weeks since birth.
How many days old is my baby?
Multiply the number of years by 365 (add 1 for leap years). For a 2-year-old baby, that is 2 x 365 = 730 days (or 731 if one year was a leap year). The calculator handles leap years automatically for accurate results.
When will my baby be 6 months old?
A baby reaches 6 months old exactly 6 calendar months after their birth date. For example, a baby born on January 15, 2025, will be 6 months old on July 15, 2025. The milestone calendar in the calculator shows the exact date and day of the week for every monthly milestone up to 24 months.
Is this calculator free?
Yes, the baby age calculator is completely free to use with no registration required. You can share results via URL — all your inputs are saved in the URL so you can bookmark or share the exact calculation.
How do I calculate baby age in weeks to months?
To convert baby age from weeks to months, divide the number of weeks by 4.345. For example, a 35-week-old baby is 35 / 4.345 = 8.06 months old (approximately 8 months). The calculator shows both total weeks and total months for easy conversion.
How can tracking baby age by months help with vaccination schedules?
Vaccination schedules for newborns are based on how many months old the child is. Milestones at 6 weeks, 10 weeks, 14 weeks, 9 months, 12 months, and 18 months are common vaccination points. Our baby age calculator helps parents track these critical ages so they never miss a scheduled immunization.