Age Calculator
Enter a date of birth and this page returns the exact age in years, months and days, the total number of days lived, the weekday of birth, and a live countdown to the next birthday. Every calculation happens in your browser; the date you type never leaves your device.
Pick a birth date to see an exact age breakdown and a live countdown to the next birthday.
How the age calculator works
Your age is the gap between two calendar dates: the day you were born and today. That sounds simple, but stating it as a clean number of years, months and days takes a little care because months have different lengths and some years contain a leap day. This calculator does the counting the same way a person would, borrowing from the previous month when the day of the month has not yet come around.
For example, if today is the 5th and you were born on the 20th, the current month is not complete, so we borrow the full length of the previous month and reduce the month count by one. Doing this in the right order gives an age that always reads naturally, such as 34 years, 2 months and 11 days.
Total days, weeks and hours
Alongside the years, months and days breakdown, the tool reports your life in single units. Total days is the count of midnights between your birth date and today, which automatically includes every leap day you have lived through. Total weeks is that day count divided by seven, and total hours and minutes come straight from the elapsed time. These figures update live, so the minutes tick upward while the page is open.
Leap years and February 29 birthdays
A leap year adds February 29 to keep the calendar aligned with the Earth's orbit, which takes about 365.2422 days. Years divisible by four are leap years, except century years, which must also be divisible by 400. That is why 2000 was a leap year but 1900 was not. If you were born on February 29, the countdown to your next birthday rolls to March 1 in ordinary years, so you never miss a celebration.
Time zones and daylight saving
Because age is measured in whole days, the hour of your birth does not change the years, months and days figure. The calculator uses your device's local calendar to decide what counts as today, so the result matches the date on your wall. Daylight saving shifts do not affect the day count either, since they move the clock, not the calendar.
Worked examples
The awkward cases are the ones worth showing, because they are where two calculators disagree. Each row below is the answer this tool gives, and the reason it gives it.
| Born | On | Age | Why |
|---|---|---|---|
| 29 February 2004 | 28 February 2025 | 20 years, 11 months, 30 days | The day of the month has not been reached, so the person is not yet 21. Some legal systems disagree and treat 28 February as the birthday in a common year; where the difference matters, the law of the jurisdiction decides, not a calculator. |
| 29 February 2004 | 1 March 2025 | 21 years, 0 months, 1 day | March has arrived, so the year has completed. This is the reading most common-law jurisdictions use. |
| 31 January 2026 | 28 February 2026 | 0 years, 0 months, 28 days | A whole month has not passed, because there is no 31 February to reach. The days are counted against the length of January. |
| 31 January 2026 | 31 March 2026 | 0 years, 2 months, 0 days | Both month boundaries land exactly, so it is clean. |
| 12 June 1990 | 12 June 2026 | 36 years, 0 months, 0 days | A birthday is a whole number of years, with the day itself counting as the moment the year completes. |
When this is not the answer you want
Age in whole calendar days is the right measure for almost everything, but not for all of it. Gestational age is counted in completed weeks from a different origin. Some insurance and pension rules use age at nearest birthday rather than age last birthday. A few jurisdictions count a leap-day birthday as 28 February. If a form or a contract defines age differently, the definition in the document wins over the number here.
Counting to a specific birthday rather than from one? The date calculator handles any two dates, and if you were born on a leap day the countdown to the next 29 February is probably what you are actually after.
Frequently asked questions
How is my exact age calculated?
We subtract your birth date from today's date using calendar-aware borrowing. Months and days are counted the way people naturally state an age, so a person born on January 31 becomes one month old on the last day of February, then two months old on March 31.
How do you handle leap years?
Total-day counts include every February 29 that fell within your lifetime, so leap years are counted exactly. If you were born on February 29, your birthday countdown rolls to March 1 in years that do not have a leap day.
Does the age calculator use my time zone?
Yes. The calculation uses your device's local date, so 'today' matches the calendar you see. Because ages are measured in whole days, the exact hour and minute do not change the years, months and days result.
How many days old am I?
Enter your birth date above and the tool shows your total days alive, along with total weeks, hours and minutes. The day count is the number of midnights between your birth date and today.
Is my birth date sent anywhere?
No. Every calculation runs in your browser with plain JavaScript. Nothing is uploaded, stored on a server, or tracked.
Method described on the about page. Last updated 2026-08-05.
Related tools
Keep the date math going with the rest of the toolkit.