How exact age is calculated
Your age is counted in whole calendar units, the same way official documents do it: complete years since your date of birth, then complete months since your most recent birthday anniversary, then the days left over. Because months vary between 28 and 31 days, the months-and-days part depends on the calendar itself, not just on the raw number of days elapsed.
The total days alive figure is the simpler measure: the exact count of days between your birth date and the chosen date. Divide it by 365.25 and you will land very close to your age in years, with the small difference coming from how leap years fall.
Frequently asked questions
How is exact age calculated?
Full years first, then full months, then remaining days. Because months have different lengths, two people born the same number of days apart can show slightly different months-and-days breakdowns.
What if I was born on 29 February?
In non-leap years this calculator treats 1 March as the anniversary, the most common convention. Some places use 28 February; either way the difference is a single day at the boundary.
Why does my age differ in some countries?
This calculator uses the international convention of completed years. Traditional East Asian reckoning historically counted a person as one at birth and added a year each New Year, reading one or two years higher.