How it works
The calculator counts your age the way people say it out loud: full years first, then the remaining full months, then the remaining days.
- Years and months: it finds the latest monthly anniversary of your birth date that is not after today. The number of whole months up to that day, split into years and months, gives the first two parts of your age.
- Days: the days from that anniversary to today are the third part.
- Totals: total days are the calendar days between your birth date and today; total weeks are those days divided by 7, rounded down.
“Today” is the current date in your device’s time zone, so the result is right even late at night or while traveling.
Example
Born on May 15, 1990, calculated on October 1, 2026.
- The latest anniversary is September 15, 2026 — that is 36 years and 4 months after the birth date.
- From September 15 to October 1 there are 16 days.
- Age: 36 years, 4 months, 16 days — 13,288 days or 1,898 full weeks.
- The next birthday, May 15, 2027, is 226 days away.
Notes and assumptions
- Months have different lengths. When an anniversary falls on a day that doesn’t exist in a month (for example, the 31st), the last day of that month is used.
- Leap-day birthdays: if you were born on February 29, your birthday falls on February 28 in years that are not leap years. The same rule applies to the age itself, so the result stays consistent.
- Time zone: the date of “today” comes from your device. Before the page has loaded fully, the result is shown as of the date printed below it.
- The calculator works with calendar dates only; time of birth is not considered.
- Your date of birth is not stored. It only appears in the page address if you change it, so you can share or bookmark the result.
Frequently asked questions
Why is my age in days different from another calculator?
Calculators differ in whether they count the birth date, today, or both. This one counts the days between the two dates, like the difference on a calendar: from yesterday to today is 1 day.
How is a February 29 birthday handled?
In common years, your birthday and your age move on February 28. In leap years, they use February 29 as usual.
Can I calculate the age of something other than a person?
Yes. Any start date works — a company’s founding date, an anniversary or a pet’s birthday.
Why can’t I enter a future date?
An age can only be calculated for dates up to today. If you want to know how long until a future date, that needs a date-difference calculator.