Find answers to common questions about age calculation, date differences, and how our tools work.
Age is calculated by comparing your date of birth to the current date (or a date you specify). The calculation first finds the difference in years between the two dates, then adjusts for whether the month and day of the birth date have been reached in the target year to arrive at the exact years, months, and days.
Yes, our calculators fully account for leap years. The date math evaluates each year individually to determine whether it has 365 or 366 days, and February is handled correctly with either 28 or 29 days depending on the year. The Gregorian calendar leap year rules are followed: a year is a leap year if it is divisible by 4, except if it is divisible by 100, unless it is also divisible by 400.
The date difference is calculated by first determining the whole-year and whole-month differences between the start and end dates, then adjusting for any remaining days. The total days count is the absolute number of calendar days between the two dates, which is then used to derive total weeks and total months.
All calculations use the Gregorian calendar, which is the internationally accepted civil calendar. This is the same calendar system used by your computer and browser. It accurately handles dates from 100 AD to approximately 275,760 AD.
Yes, you can use the Age Calculator with a future "as of" date to determine what your age will be on that date. The calculator will show your future age in years, months, and days.
No, all calculations are performed entirely in your browser. No data is sent to any server, saved, or shared with third parties. Your date of birth and other inputs are processed locally on your device.