Age Calculator
Calculate your exact age in years, months, weeks, and days. Free, fast, and accurate age calculator.
Table of Contents
How to Use the Age Calculator
- Enter your date of birth in the first field. You can also click one of the Try buttons for a quick example.
- Set the second date — this is the date you want to calculate your age as of. Leave it blank to use today.
- Your age updates instantly, shown in years, months, weeks, days, hours, minutes, and seconds.
- Use the Use today button to reset the second date to the current date, or share your result with the share button.
What Is an Age Calculator?
An age calculator determines the amount of time that has passed between a starting date — usually a date of birth — and another date. It expresses the result in years, months, and days, the same way people naturally describe age.
This calculator uses the most common Western age system, where age increases on your birthday. For example, someone who has lived 3 years and 11 months is 3 years old, and turns 4 on their next birthday.
How to Calculate Age
Age = (Later Date) − (Date of Birth), counted in years, months, and days
Start with the year difference between the two dates. If the later date's month and day haven't yet reached the birth month and day, subtract one year.
Next, find the month difference. If the day of the later date is before the birth day, subtract one month.
Finally, count the remaining days. Weeks, days, hours, minutes, and seconds are derived from the exact elapsed time between the two dates.
Leap Years and Uneven Months
Because months have different numbers of days and leap years add an extra day in February, age in days can vary slightly between methods. This calculator counts calendar months and days the standard way, so February 28 to March 28 is treated as one month.