Age calculator: exact age in years, months and days
Your exact age in years, months and days — leap-day-safe, with the day of the week you were born.
Breakdown
- Ages are completed years, months and days — the way ages are stated, with months of different lengths handled by the calendar, not averaged.
- A 29 February birth is counted exactly; the tool never silently moves it to another date.
- Dates are plain calendar dates — no time zones, so the result is the same everywhere.
- Nothing you enter leaves your browser.
Enter a date of birth and the calculator gives you the exact age on any date you choose: completed years, then months, then days, along with the total days lived, the weekday of the birth, and when the next birthday falls. It reads the real calendar, so the answer is exact rather than an estimate.
How it counts
Age is stated the way people say it out loud: the number of completed years first, then the leftover months, then the leftover days. You are 36 the day you finish your 36th year, not the day you begin it.
The calculator works down through those three units in order. It counts every full year that has passed since the birth date, then every full month on top of that, then the days left over. It reads month lengths from the calendar itself, so February is 28 or 29 days as the year demands and the long months are 31. Nothing is averaged to “about 30 days”, which is what makes the day count exact rather than close.
The 29 February case
A birth on 29 February is counted exactly, against the real calendar. The date itself only comes back in a leap year, so the calculator names the next 29 February when it lands rather than pretending one exists every year.
In the three years between leap days there is no 29 February to land on, so a birthday has to be observed on another day. Marking it on 28 February or on 1 March is a matter of convention for most people. In some places it is also a legal definition, used to fix the day someone reaches a given age for the purpose of a licence, a pension or a contract, and the rule differs from country to country. The calculator counts the exact elapsed time; which neighbouring day you choose to celebrate on is yours to decide.
A worked example
Take someone born on 7 July 1990. On 7 July 2026 they turn exactly 36: thirty-six full years have passed, with no leftover months or days, because the age-on date is their birthday. Across those years they have lived 13,149 days. The extra days beyond a plain 36 times 365 are the leap days that fell inside the span, each one added by the calendar rather than by a rule of thumb.
Method note
The tool does plain calendar arithmetic. It compares two dates and reports the gap in the units people use for age. There are no time zones and no clock times: a date is a date wherever you are, so the same birth date and the same age-on date give the same answer in Berlin, Boston or Bangalore.
Everything is computed in your browser as you type. Nothing you enter is sent anywhere or stored; close the page and the dates are gone.
To go the other way and measure the span between any two dates in days or weeks, use the date calculator. Leap years and leap-day birthdays sit behind the exact counting here.
Questions people ask
How do I work out my exact age in years, months and days?
Work out your exact age by counting completed calendar units in order: full years since birth, then full months, then whatever days are left over. Someone born on 7 July 1990 is exactly 36 years, 0 months and 0 days old on 7 July 2026, having lived 13,149 days. An age calculator does this in one step and handles 29 February birthdays exactly, so you never have to work out leap-year rules by hand.
Updated 7 July 2026