How is age calculated?
Age is calculated by finding the difference between your date of birth and today's date (or any target date you choose). The calculation accounts for leap years, varying month lengths, and the exact time of day to give you a precise result down to the minute.
The most common way to express age is in completed years — meaning you are not considered a year older until your actual birthday has passed. So if you were born on December 31 and today is December 30, you are still the previous age even though you are one day away from your birthday.
Why does age matter?
Age is used in countless important decisions: eligibility for driving licences, voting, retirement benefits, school enrolment, health screening guidelines, and insurance pricing. Knowing your exact age in days or months can also be useful for medical contexts, legal documents, and milestone planning.
Interesting age facts
- If you are 30 years old, you have lived approximately 10,950 days or 262,800 hours.
- People born on February 29 (leap day) only have a "real" birthday every 4 years — they are technically only a quarter of their age in birthdays.
- The oldest verified human ever was Jeanne Calment of France, who lived to 122 years and 164 days.
- In South Korea, a different age system is traditionally used — everyone becomes one year older on New Year's Day rather than on their birthday.
- In many cultures, turning 60 or 61 is celebrated as a second birth — a full return through the zodiac cycle.