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Baby Age Calculator
Your baby's birth date
Example: born August 20, 2025 — 14 months old on November 8, 2026 (1 year, 2 months, 19 days; 445 days).
Behind the numbers
How your baby's age is calculated
The calculator counts from the date of birth to today in the same way as the child age calculator: full years, then full months, then leftover days. Because babies change so quickly, it also shows the total months (14 months is easier to compare with milestone charts than "1 year 2 months"), the total weeks, and the total days. Under the result you will see a short milestones note for your baby’s current age band — a rough guide only, since every baby develops at their own pace.
For a baby born August 20, 2025, measured on November 8, 2026: total months = (2026 − 2025) × 12 + (11 − 8) − 1 = 14 months (one is subtracted because the 8th is before the 20th, so the 15th month has not started). In years, months and days that is 1 year, 2 months and 19 days. Total days = 445, and 445 ÷ 7 = 63 weeks with 4 days left over.
Examples
Example baby ages (on November 8, 2026)
| Date of birth | Age in months | Weeks | Days |
|---|---|---|---|
| August 20, 2025 | 14 months (1 yr, 2 mo, 19 days) | 63 | 445 |
| May 10, 2026 | 5 months, 29 days | 26 | 182 |
| February 1, 2026 | 9 months, 7 days | 40 | 280 |
| November 8, 2025 | 12 months (1 year) | 52 | 365 |
Tips
Doctors and milestone charts use months up to age 2, so "14 months" is the number to quote at checkups, not "1 year old."
Weeks are useful in the first months — for example, vaccine schedules are often given in weeks.
Milestones are ranges, not deadlines. Many healthy babies walk anywhere from 9 to 18 months.
For a premature baby, doctors often use the "adjusted age" (age from the due date, not the birth date) for milestones in the first two years — ask your pediatrician.
Good to know
Frequently asked questions
Why is baby age given in months instead of years?
Because a baby changes so much month to month. Saying "14 months" tells a doctor or another parent far more than "1 year old," which could mean anything from 12 to 23 months.
How many weeks old is my baby?
Divide the total days since birth by 7. A baby born August 20, 2025 is 445 days old on November 8, 2026, which is 63 weeks and 4 days.
When do parents stop counting in months?
Most people switch to years around age 2, when growth slows down and month-to-month changes get smaller. Doctors usually keep using months until age 2 as well.
My baby was born early. Should I use the birth date or the due date?
For milestones in the first two years, pediatricians often use the adjusted age — counted from the due date. For legal age, birthdays and this calculator, use the actual birth date. Ask your pediatrician which one they want.