Age calculator
Type a date of birth (and optionally a reference date) to get an exact age in years, months, days, hours, and seconds.
What this tool does
Type a date of birth and the tool calculates the exact age as of today — or as of any other date you specify. The result is broken down into years, months, and days, plus total days, total hours, and total minutes.
How the math works
The "exact age" is computed by walking backwards from the reference date: count full years, subtract that span, then count full months, subtract, then count remaining days. This matches the way most legal systems and registrars compute ages. Note that it is not a simple division of total days by 365.25 — the calendar is irregular, with months of 28 to 31 days and leap years every four years (with century corrections).
Leap years and February 29
People born on February 29 only have a true birthday once every four years. Legally, most jurisdictions treat them as having a birthday on either February 28 (most common) or March 1 (Taiwan, Hong Kong) in non-leap years. This calculator displays the literal calendar date, which means a Feb 29 birthday won't appear in non-leap years; the "years" count still increments correctly on March 1.
What "exact age" means in different systems
Most of the world reckons age by counting completed years since birth. The traditional East Asian system (still used in Korea for some purposes) counts a person as one year old at birth and adds another year at each Lunar New Year, making a child up to two years "older" than their Western age. This calculator uses the Western system.
Time zones
The calculator treats the date of birth and reference date as plain calendar dates with no time zone. For births that happened near midnight, this can shift the count by a day depending on where the person was born versus where you are calculating from. For legal-age determinations, consult the relevant authority.
Privacy
Dates are processed in your browser and never sent anywhere.