Baby Age in Months

How many months old is my baby calculator — get exact age in months, weeks and days. Use the free Baby Age in Months below — enter your values and get instant results, right in your browser. Logic: age = as-of date − birthdate using real calendar arithmetic at UTC midnight. Total months = years × 12 + remaining months; total days and weeks come from the exact day count including leap days.

How to use the Baby Age in Months

In the first two years, every parent talks in months — "she is 14 months old" — but counting months from a birthdate across different month lengths is surprisingly tricky. This how many months old is my baby calculator gives the exact age in years, months and days, plus total days and weeks lived, from just the birthdate. Perfect for milestone photos, vaccination schedules and answering relatives precisely.

  1. Open the Age tab of the calculator.
  2. Enter your baby's date of birth in the birthdate field.
  3. Keep the "as of" date on today for the current age.
  4. Click Calculate to see the full age breakdown.
  5. Read the months count plus total days and weeks for milestone posts.

Formula

Logic: age = as-of date − birthdate using real calendar arithmetic at UTC midnight. Total months = years × 12 + remaining months; total days and weeks come from the exact day count including leap days.

Worked example

Born 20 June 2025, as of 12 October 2026. Click Calculate. Result: 1 year, 3 months, 22 days — that is 15 months old, or 479 days (68 weeks). Ideal caption for the 15-month milestone photo — and the total-days figure helps with vaccination schedules counted in days.

Frequently asked questions

Usually until 24 months (2 years), when parents switch to saying years. Doctors track months closely for growth charts.

It counts from the actual birthdate. For medical milestones, doctors may use "corrected age" — ask your pediatrician.

Yes. Set the "as of" date to an upcoming date to see exactly how old your baby will be then.