Age Calculator
Enter a date of birth to find your exact age in years, plus days until your next birthday and the total number of days you have been alive.
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Input
Result
Enter a date of birth and an as-of date.
How it works
- Enter your date of birth and an as-of date (the date you want your age for; today by default). Your age is the number of times your birthday has occurred up to and including the as-of date.
- “Days until next birthday” counts from the as-of date to your next birthday. If the as-of date is your birthday, it shows 0.
- “Days since birth” is the total number of calendar days between your date of birth and the as-of date.
- Kazoe age is a traditional East Asian way of counting: you are 1 at birth and gain a year every New Year's Day. It is shown for reference.
- Ages are counted up by one on each birthday (the everyday method). All calculations run in your browser.
Worked example: born February 15, 1990
Enter February 15, 1990 as the date of birth and October 23, 2026 as the as-of date. Subtracting the years gives 2026 − 1990 = 36. The 2026 birthday on February 15 has already passed by October 23, so the age is 36. Had the as-of date been February 14, 2026, the birthday would not yet have arrived and you would subtract one, giving 35.
The same entry shows the next birthday as February 15, 2027, 115 days away, and a total of 13,399 days since birth. The day total is a plain count of calendar days and includes every leap day along the way.
Age last birthday versus age nearest birthday
The age shown is the completed number of years, sometimes called age last birthday. It is the figure used on most forms, ID checks and eligibility rules. Some life insurers and annuity providers price on age nearest birthday instead, where you are rounded up once you are more than about six months past your last birthday. Definitions vary by company. Use the days-until-next-birthday figure to see which side of that halfway point you are on: someone 115 days from their next birthday is past it.
Leap-day birthdays and other edge cases
For someone born on February 29, the calculator treats March 1 as the birthday in common years. Born February 29, 2000? On February 28, 2027 the tool shows 26 with 1 day to go. On March 1, 2027 it shows 27 and marks the birthday. In 2028, a leap year, the birthday is February 29 itself.
Laws differ on this point. Some jurisdictions treat February 28 as the date a leap-day person reaches a new age in common years, and others use March 1. If a legal age threshold depends on it, check the rule where you live rather than relying on any calculator.
- Before or after the birthday: the age only rises when the as-of date reaches the birthday, never on the day before.
- Future dates: set the as-of date to a deadline, for example an application cut-off or a travel date, to see how old someone will be on that day.
- Days since birth: born October 23, 1996? On October 23, 2026 you are 10,957 days old, which is 30 × 365 plus 7 leap days.
What is kazoe age?
The calculator also shows kazoe age, the traditional East Asian way of counting. You are 1 in your year of birth and gain a year every January 1, regardless of your birthday. Kazoe age is the calendar-year difference plus one, so someone born in 1990 has a kazoe age of 37 throughout 2026.
The gap with ordinary age is 2 years from January 1 until your birthday and 1 year after it. A baby born on December 31, 2025 is 0 years old but kazoe age 2 on January 1, 2026. South Korea, whose traditional age worked the same way, standardized on international age for legal and administrative purposes in June 2023. In Japan, kazoe age survives mainly in some traditional customs and ceremonies.
Frequently asked questions
- How is my exact age calculated?
- Your age increases by one on each birthday, so we count the number of full years from your date of birth to the reference date (today by default). Change the reference date to see your age at any past or future point in time.
- How are the days until my next birthday counted?
- We count the remaining days from the reference date to your upcoming birthday and show the age you will turn on that day. If the reference date is your birthday, it indicates that today is the day.
- What does the total number of days alive mean?
- It is the running total of days from your date of birth to the reference date, which is handy for checking anniversaries or which day-number a milestone falls on. Leap years are accounted for automatically.
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