Age Calculator
Enter your date of birth to calculate your exact age in years, months, and days, plus how many days remain until your next birthday.
About This Tool
Calculating age looks simple but involves many subtleties: months between two birthdays vary in length (28, 29, 30, or 31 days), so the exact "years, months, days" expression isn't always equal to a simple division of total days.
This tool uses an exact calendar algorithm: starting from the date of birth, it first counts whole years, then remaining whole months, then remaining days, ensuring the "years, months, days" result matches the calendar exactly. For example, someone born on June 15, 1995 is exactly 31 years, 5 months, 0 days old on November 15, 2026.
The tool also provides two fun reference numbers: your total days on Earth and how many days until your next birthday. Total days are counted by real calendar days (leap years included), and the next birthday automatically accounts for whether this year's has already passed.
How to Use
- Click the "Date of Birth" input and pick your birth date from the calendar.
- Click the "Calculate Age" button.
- View your exact age, total days, and days until your next birthday.
Frequently Asked Questions
What is the difference between exact age and traditional counting age?
Exact age counts the time actually lived: you are 0 at birth and gain 1 year after each anniversary of your birthday — it is the legal and international standard. The traditional counting age starts at 1 at birth and gains a year at each Lunar New Year; it is a folk custom. This tool calculates exact age.
What if the birthday is February 29 (a leap day)?
In non-leap years without February 29, the tool treats the birthday as falling between February 28 and March 1, so the day count for age growth remains accurate. Days until the next birthday use February 28 as the reference date in non-leap years.
Can the days in "years, months, days" be negative?
No. The tool uses a borrow algorithm: when there aren't enough days to subtract, it borrows a full month (28–31 days) from the previous month, so all three values are non-negative and consistent with the calendar.
Can it calculate a baby's age in months?
Yes. Just enter the baby's date of birth — the "months, days" part of the result is exactly how infant age is commonly expressed.
Will my date of birth be saved?
No. All calculations run locally in your browser; this site does not collect, upload, or store any date information you enter.