Home Age calculator
Age calculator
Find an exact age in years, months, days, and total days. A February 29 birthday uses February 28 in a non-leap year. Dates stay in this browser.
Why this exists
Dividing the day count by 365 drops the leap days, so the birthday lands on the wrong day.
A form asks for an age on a date that is not today, and the month ends are easy to miscount.
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01How to use it
Pick the birth date, then the date to count to. Today fills the second date with this device’s date.
The large line is years, months, and days. Under it are the total days, the weeks, the next birthday, and the weekday of birth.
Copy puts that line on the clipboard. Closing the tab clears the dates.
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02What you get
15 March 1990 counted to 7 November 2026 is 36 years, 7 months, 23 days, which is 13386 days.
29 February 2000 counted to 28 February 2023 is 23 years, 0 months, 0 days. The next day, 1 March 2023, is 23 years, 0 months, 1 day.
Entered1990-03-15 → 2026-11-07
1990-03-15 → 2026-11-07 36 years, 7 months, 23 days · 13386 days 2000-02-29 → 2023-02-28 23 years, 0 months, 0 days 2000-02-29 → 2023-03-01 23 years, 0 months, 1 day 2000-01-31 → 2026-03-01 26 years, 1 month, 1 day -
03Worth knowing
This is the age counted from the birthday. It does not add a year at New Year.
31 January uses the last day of February as that month’s anniversary. 31 January 2000 to 1 March 2026 is 26 years, 1 month, 1 day.
The weekday comes from the calendar date alone. A time zone is not added, because a date has no clock.
A date that is not a real day, such as 31 April, is refused.
Questions
- QIs 1 March the birthday for someone born on 29 February?
- ANo. In a year without 29 February the anniversary is 28 February. On 1 March the age is one day older.
- QIs 15 March 1990 to 7 November 2026 exactly 36?
- AIt is 36 years, 7 months, and 23 days, or 13386 days. The age has not reached 37.
- QCan the second date be in the past?
- AYes. Any real date on or after the birthday works, including a past date.
- QAre the dates saved?
- ANo. They stay in this browser and are not sent to a server.
How this page works it out
The age is counted on the calendar from the birthday to the date you choose. A day that month does not have uses the last day of the month. A February 29 birthday stays on February 29 in a leap year and falls on February 28 in any other year. March 1 is already one day into the new year of age.
The birth date is day 0, and the day count is the number of midnights between the two dates. 15 March 1990 counted to 7 November 2026 is 36 years, 7 months, 23 days, or 13386 days. 31 January 2000 to 1 March 2026 is 26 years, 1 month, 1 day.
This page does not add a year at New Year. A date that is not real, such as 31 April, is refused, and a birth date later than the second date stops the sum. The dates stay in this browser.