Age in Months Calculator

Find your exact age in months and remaining days.

Age in months

374 months

and 7 days

Years and months

31 y 2 m

Total weeks

1,627

Total days

11,391

Average days per month

30.46

Complete calendar months from the date of birth, plus the leftover days.

Paediatric records and school admission cut-offs use months and days, which is why the leftover days are shown separately.

What does Age in Months Calculator do?

Calculate age in complete months plus leftover days — the form used for infant development milestones, paediatric records, school admission cut-offs and insurance age bands.

How to Use Age in Months Calculator

1
Enter the date of birthOr any starting date.
2
Set the reference dateDefaults to today.
3
Read the ageIn complete months plus days.

Key Features

Complete months plus the leftover days
Total weeks and days shown alongside
Corrected age option for premature infants
Age as of any reference date, not just today
Years-and-months breakdown for forms that ask for it

Frequently Asked Questions

How is age in months calculated?

By counting complete calendar months from the birth date. A baby born on 15 March is 3 months old on 15 June and 3 months and 10 days old on 25 June.

What is corrected age?

For a premature baby, the age adjusted for how early they arrived — chronological age minus the weeks of prematurity. Paediatricians use it when assessing development milestones, typically until age two.

Why do school admissions use months?

Because eligibility is set by an exact cut-off date, and a child a few days either side falls in a different intake year. Months-and-days precision is what determines it.

How many months old is a one-year-old?

Twelve. After that, most people switch to years, though paediatric records commonly continue in months up to 36 because development varies so much in those years.

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