Age Calculator

Exact age is calculated in three steps. First, subtract the birth year from the target year to get a raw year count. Then subtract birth month from target month; if the target day is earlier in the month than the birth day, borrow one month and add the number of days in the previous month to the day difference. Finally, if months become negative, borrow a year and add 12. This handles February, leap years, and month-length variations automatically — it is the same method courts and governments use for legal age determination.

The age of majority (when a person is legally considered an adult) varies by country: India — 18 years (21 under the Hindu Minority and Guardianship Act in some contexts); United States — 18 years (19 in Alabama and Nebraska, 21 in Mississippi for certain purposes); United Kingdom — 18 years; Japan — 18 years (changed from 20 in April 2022); Canada — 18 or 19 depending on the province; Germany, France, Australia — 18 years. Use the calculator above to find the exact date on which any person reaches a milestone age.

Your age in days is the total number of calendar days between your date of birth and today, inclusive of leap days. For example, someone born on 1 January 2000 is 9,677 days old on 24 June 2026. You can see your exact total-day count in the "Total days" result above. Interestingly, 1 billion seconds equals approximately 31.7 years, so you pass the 1-billion-second mark a little over 31 and a half years after your birth.

The calculator automatically determines your day of birth from your date of birth using JavaScript's Date API, which applies the proleptic Gregorian calendar. For dates before 15 October 1582 (when the Gregorian calendar was adopted) the result is extrapolated and may differ from historical Julian-calendar records. For modern dates (after 1582) the day-of-week result is reliable.

Use the "As of" date field. By default it is set to today, but you can change it to any past or future date. This lets you answer questions like "How old will I be on my wedding date?", "How old was my grandfather when he emigrated in 1965?", or "How old will I be when I retire in 2045?" The calculator uses the exact same years/months/days algorithm regardless of whether the "as of" date is in the past or future.

Chronological age is the time elapsed since birth measured in calendar years, months, and days — exactly what this calculator computes. It is different from biological age (how old your body functions physiologically), mental age (cognitive development level), or social age (life-stage milestones). Legal and administrative contexts always use chronological age. Some cultures use a different age-counting system — for example, in traditional Korean age reckoning, a person is considered 1 year old at birth and gains a year on every New Year's Day rather than their birthday.