Exact age calculator
Exact age between a birth date and any reference date: years, months and days, total days, weeks, hours and minutes, the countdown to the next birthday, leap days passed and the weekday you were born on.
Runs in your browserEvery computation happens in your browser — your data never leaves this device.
Dates
Dates are computed in UTC so the local time zone cannot shift them, and a 29 February birthday is treated as 28 February in common years. Leave the reference date empty to use today.
Result
Enter a date of birth to see the result.
What this tool does
- See exactly how many days, weeks and hours you have been alive by entering a birth date.
- Plan a birthday party: the countdown to the next birthday beats counting days on a calendar.
- Get a precise years-months-days age for a form — handy for people born at the end of a month, where mental arithmetic goes wrong.
- For a leap-day baby, see the 28 February convention in common years and how many 29 Februaries have passed.
Example
Input
Date of birth 1990-05-20, calculated up to 2026-10-10
Output
Exact age 36 years 4 months 20 days, total days 13292, total weeks 1898, total months 436, total hours 319008, total minutes 19140480, next birthday 2027-05-20 (in 222 days), 29 Februaries passed 9, weekday of birth Sunday
The 13292 total days match an independent calculation with Python’s datetime, which confirms the year/month/day borrowing logic.
Frequently asked questions
Why does “total days ÷ 365” not match the age?
Leap years. From 1990-05-20 to 2026-10-10 is 13292 days, about 36.4 years when divided by 365.25, while the exact age is 36 years 4 months 20 days. Use years/months/days for forms and total days for statistics.
How are 29 February birthdays handled?
With the usual convention: 28 February in common years. So someone born on 2000-02-29 sees “birthday today” with a zero countdown on 2001-02-28, and on 2001-03-01 is shown as 1 year 0 months 1 day old.
What does “29 Februaries passed” mean?
It counts the actual 29 February dates between the birth date and the reference date, excluding the birth day itself. That is close to, but not the same as, the number of leap years elapsed — a 29 February birth does not count its own day.
Does the result change with my time zone?
No. Dates are computed in UTC from the year, month and day you enter, so time zones, daylight saving and system date formats cannot shift the result. Only an empty reference date reads the local “today”, once, after the island mounts in the browser.
Can I use a future date or measure a difference between two dates?
The reference date can be in the future, but the birth date cannot be later than it — that raises an error. The maximum span is 200 years, beyond which the tool asks you to check the input.
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