Age Calculator
Enter your date of birth to find your exact age in years, months, and days, how many days you've been alive, which day of the week you were born on, and how long until your next birthday.
How exact age is calculated in years, months, and days
Your age isn't just a division by 365: months have different lengths (28, 29, 30, or 31 days) and every four years there's a February 29. The correct method follows the calendar: first count the full years completed, then the whole months since your last birthday, and finally the remaining days. That's the same method used on official forms and documents, and it's exactly what this tool applies.
When a day doesn't exist in the month
Months are counted on the calendar, and sometimes the starting day doesn't exist in the month you land on. In that case the page takes the last day of the month: one month after January 31 is February 28 (29 in leap years), and one month after March 31 is April 30. From January 31, 2000 to March 1, 2023 the age is therefore 23 years, 1 month and 1 day: the days never go below zero.
For the same reason, if you were born on February 29, in non-leap years your birthday here falls on February 28. It's the common calendar rule for counting in months and years, the one date libraries in software use, and the only one that keeps age and birthday in agreement: on February 28 the age shows whole years and the page wishes you a happy birthday. Celebrating on March 1 has its reasons too, but with that rule on February 28 your age would come out as 11 months and 30 days. When the birthday falls on the 28th, the page says so next to the date.
The sister page
If all you need is the days, weeks and months you have lived, there's Days lived, which does the same calculation with the same calendar: for the same date of birth, the two pages give the same numbers.
Fun milestones: counting your life in days
Measuring life in days reveals some unusual anniversaries: you hit 10,000 days shortly after turning 27, 20,000 around age 54, and 30,000 at about 82. Weeks tell a story too: an average lifespan works out to roughly 4,000 weeks. Looking at these numbers is a different, and for many people more tangible, way to feel time passing, and a great excuse to throw an out-of-the-ordinary party.