How the age calculation works
- Years: the number of birthdays that have passed on or before the “age at” date.
- Months: whole months since the most recent birthday.
- Days: the remaining days after those whole months.
Leap years are handled automatically. Totals (days, weeks, hours) count the exact number of calendar days between the two dates.
Age in different cultures
This calculator uses the international (Western) system, in which you are 0 at birth and gain a year on each birthday. Some East Asian traditions count a baby as one year old at birth and add a year at the new year; South Korea officially moved to the international system for legal purposes in 2023.
Need the time between any two dates instead? Use the days between dates calculator.
How to use the calculator
- Enter the date of birth.
- Optionally change the “age on” date to find the age on a past or future date (it defaults to today).
- Read the exact age in years, months and days, plus totals in months, weeks, days and hours, and the countdown to the next birthday.
Birthdays on February 29
People born on February 29 (“leaplings”) have an actual birthday only every four years. For legal purposes many jurisdictions treat March 1 as the birthday in non-leap years — for example the UK and Hong Kong — while others use February 28. The calculator counts a full year from February 29 to February 28 in a non-leap year, which matches the most common everyday convention; check local rules for legal deadlines such as driving age.
Age milestones (United States)
- 16: minimum age for a driver’s license in most states (with restrictions).
- 18: voting, adulthood for most legal purposes.
- 21: legal drinking age.
- 26: the age until which children can stay on a parent’s health insurance.
- 50: catch-up contributions to 401(k) and IRA retirement accounts begin.
- 59½: penalty-free withdrawals from most retirement accounts.
- 62 / 67: earliest Social Security retirement benefits and full retirement age for people born in 1960 or later.
- 65: Medicare eligibility.
- 73: required minimum distributions begin for most people under current law.
Fun facts about age
- You turn 10,000 days old at about 27 years and 4 months, and 1 billion seconds old at about 31 years and 8 months.
- Your birthday falls on the next day of the week each year, or two days later after February 29.
- Calendars repeat exactly every 28 years in most cases, so you may get the same weekday-date combination at 28 and 56.
For an age expressed in years;months.days for test scoring, use the chronological age calculator.