How is age in months and days worked out?

The tool counts complete months between the two dates, then adds the leftover days. For example, someone born on 15 January measured on 20 March is 2 months and 5 days old. It also shows the same age expressed as years, months and days.

Why is this useful for babies and toddlers?

Infant milestones, vaccination schedules and growth charts are often given in months rather than years, so an exact age in months and days is more useful than a rounded age in years.

Is my date of birth uploaded anywhere?

No. The calculation is pure local date arithmetic in your browser — nothing is sent to a server or stored.

Age in Months and Days

Find an exact age in months and days from any birth date.

Age in months and days

This calculator turns two dates into an exact age in months and days. Enter a date of birth and a reference date — handy for baby milestones, vaccination schedules, growth charts and any time a rounded age in years is too coarse.

It counts the complete months first, then the leftover days, and also shows the age as years-months-days and as a total number of days — all computed locally in your browser.