Age Calculator

Features

• Exact age in years, months and days
• Total days, weeks, hours and minutes lived
• Day of the week you were born
• Countdown to the next birthday
• Calculate age as of any date, not just today

How to use it

1. Enter the date of birth.
2. Leave the second date as today, or set another date.
3. Read the exact age above.
4. The table shows the same span in other units.

Why calendar age is harder than subtracting dates

Calendar months have different lengths, so “one month later” has no fixed duration. Age is conventionally calculated by counting whole years first, then whole months, then remaining days, which is why someone born on 31 January is a month old on 28 February in a non-leap year, but the arithmetic has to handle that month boundary explicitly rather than dividing by an average month length.

Leap years add their own complications. People born on 29 February have a birthday only once every four years, and different jurisdictions take different views on when they legally turn 18 in non-leap years, some say 28 February, others 1 March. This calculator treats 1 March as the birthday in non-leap years, which is the more common convention but not universal.

There is also a cultural dimension worth knowing. The East Asian age reckoning system, still in informal use in parts of the region, counts a newborn as one year old and adds a year at each lunar new year rather than on the birthday, making someone up to two years older than their international age. South Korea officially moved to international age in 2023, but you will still encounter both.