Calculating an exact age
Working out an age in years is easy; working it out to the day is not, because months have 28 to 31 days and leap years add a 29 February every four years or so. Forms, visas, insurance, school entry rules and sports age groups often need the exact figure, as of a specific date rather than today.
Pick a birth date and an as-of date. The calculator shows the age in years, months and days, the total number of days, weeks, hours, minutes and seconds, the days until the next birthday and the zodiac sign.
How to use it
- Choose the birth date.
- Leave the as-of date at today, or change it to the date that matters, such as a deadline or an event.
- Read the age in years, months and days.
- Use the totals for questions like how many days old someone is, and the next-birthday line for planning.
Example: an age on a given day
Born 1990-05-15, as of 2026-10-26
36 years, 5 months, 11 days Total days: 13,313 Weeks: 1,901
The days part counts from the 15th of the last full month, 15 October, to 26 October.
How the counting works
The calculator first counts whole years, then whole months, then the remaining days. When the day of the month in the end date is earlier than in the birth date, it borrows the length of the previous month. That is the same method people use when they count on a calendar, and the one most official forms expect.
Total days are calendar days between the two dates, so a change to or from daylight saving time inside the range does not shift the result. Hours, minutes and seconds are those days multiplied out, assuming both dates start at midnight.
Birthdays on 29 February
People born on a leap day only have a calendar birthday every four years. In non-leap years the legal answer varies by country: some treat 28 February as the birthday, others 1 March. This tool counts months strictly, so in a non-leap year it reaches the next whole year of age on 1 March.
Other ways to count age
In parts of East Asia a traditional count started at one at birth and added a year at the new year. South Korea officially adopted international age counting for legal purposes in June 2023. If a form asks for age in a specific system, check which one it means.
Questions
Can I calculate the time between any two dates?
Yes. The birth date field accepts any date, so you can measure the length of a job, a project or a marriage the same way.
Is the zodiac sign exact?
It uses the common Western date ranges. Signs change around the 19th to 23rd of each month, and astrologers sometimes place cusp dates differently by year.
Is my birth date stored?
No. The dates stay in this tab and are never sent anywhere.