Quick Answer
Your exact age is calculated by finding the difference between your date of birth and today's date, accounting for varying month lengths and leap years, expressed in years, months, and days.
What Is Age Calculator?
An age calculator determines your precise age, not just in years, but down to the exact number of months and days, by calculating the calendar difference between your date of birth and a target date (usually today). While 'how old are you' seems simple, calculating it precisely is slightly more involved than just subtracting years, because months have different lengths and leap years add an extra day roughly every four years.
Age calculators are useful well beyond simple curiosity: they're used for eligibility checks (minimum age requirements for school enrollment, voting, retirement benefits, or specific legal contracts), for calculating exact ages for medical dosing in pediatrics, and for any situation requiring a precise age on a specific date rather than just 'years since birth.'
Some applications need age calculated as of a specific cutoff date rather than today, for example, school admission rules often specify a child must be a certain age by a particular cutoff date in the academic year, not their age on the application date.
How to Use
- 1Enter your date of birth.
- 2Optionally, enter a specific 'as of' date if you need your age on a date other than today (e.g. an eligibility cutoff date).
- 3The calculator returns your exact age in years, months, and days.
Formula
Age = (Target Date − Birth Date), normalized into years, months, and daysAccounts for varying month lengths (28-31 days) and leap years
Example: Born March 15, 2000, age as of June 21, 2026
- Birth Date = March 15, 2000
- Target Date = June 21, 2026
- Full years elapsed = 26 (birthday already passed this year)
- Remaining months = March to June = 3 months
- Remaining days = 15th to 21st = 6 days
Tips & Things to Know
- If someone was born on February 29 (a leap day), most calculators treat their birthday as February 28 (or March 1) in non-leap years, check the specific convention used for any legal or official purpose.
- Age calculated 'in years' for legal purposes (like turning 18) is typically the number of full years completed, not rounded, someone is legally a specific age starting from their exact birth date and time, not the calendar year of their birthday.
- For school cutoff calculations, always confirm the specific cutoff date your institution or jurisdiction uses, since it varies (e.g. age by September 1 vs. age by December 31).
- Time zones can technically affect exact birth-moment calculations for people born close to midnight, though this rarely matters for everyday day-level age calculations.