How to calculate your age
To calculate your exact age, enter your date of birth and choose the date you want to calculate your age on. The calculator uses today's date by default, but you can enter another date to find out how old you were or will be on a specific day.
After you select the dates, the calculator shows your age in complete years, months, and days. It also provides the total number of days, weeks, hours, minutes, and seconds, along with the date of your next birthday.
How does the age calculator work?
Age is normally measured using calendar dates rather than a fixed number of days. The calculator first determines the number of complete years between the date of birth and the selected date. It then calculates the remaining complete months and days.
This is why an age such as 35 years, 3 months, and 8 days cannot be calculated accurately by simply dividing the total number of days by 365. Calendar years can contain 365 or 366 days, and months have different lengths.
For example, someone born on March 15, 1990, and calculating their age on June 23, 2025, is 35 years, 3 months, and 8 days old. The same calculation can also be expressed as a total number of days, weeks, or hours.
What is the "Age at date" field?
The Age at date field lets you calculate your age on a date other than today. You can use it to find out how old you were on a particular date in the past or how old you will be on a future date.
For example, you can calculate your age on a graduation date, a past birthday, a historical event, or another important date. If you only need to find the number of days between two dates, try our Days Between Dates Calculator.
How many days old am I?
The calculator also shows your total age in days. This is different from multiplying your age in years by 365 because the actual number of days depends on the calendar dates involved and includes leap days.
The total-day result can be useful if you want to know approximately how many days you have lived. You can also use our Days From Today Calculator when you want to calculate a date difference relative to today.
How many months or weeks old am I?
Age can be expressed in several different ways. The calculator provides your calendar age in years, months, and days, as well as total weeks and other time units.
Remember that a calendar month is not always the same number of days. For simple unit conversions, you can also use our Months to Years Converter.
How does the calculator handle leap years?
Leap years are important when calculating an exact age because they contain an extra day. The calculator uses the actual calendar dates involved in the calculation, so leap days are included in the total day count.
February 29 birthdays require special consideration because February 29 does not occur every year. The calculator provides a convention for handling February 29 birthdays so that the next-birthday calculation can be made consistently.
You can also see our Leap Years List to check which years contain February 29.
When is my next birthday?
In addition to calculating your current age, this calculator tells you the date of your next birthday. This makes it useful for checking how long remains until your next birthday without having to calculate the date manually.
If you are interested in the halfway point between birthdays, try our Half Birthday Calculator.
Age milestones
Age milestones are often expressed in years, but they can also be represented as approximate numbers of days or weeks. The table below provides calendar-based reference values for common ages.
Frequently asked questions
How do I calculate my exact age?
Enter your date of birth and select the date you want to calculate your age on. The calculator determines the difference between the two dates and displays your age in complete years, months, and days.
Can I calculate my age on a specific date?
Yes. Enter your date of birth and use the "Age at date" field to choose any past or future date. The calculator will show how old you were or will be on that date.
How many days old am I?
The calculator displays your total number of days based on the actual calendar dates between your birth date and the selected calculation date. Leap days are included when applicable.
Does the age calculator account for leap years?
Yes. Leap years and February 29 are taken into account when calculating the difference between dates and the total number of days.
How does the calculator handle February 29 birthdays?
February 29 birthdays need a convention in years that do not contain February 29. This calculator uses the convention described in the calculator interface when determining the next birthday.
Can I calculate how old I was on a past date?
Yes. Enter your date of birth and then select the historical date in the "Age at date" field. The calculator can calculate your age on past dates as well as future dates.
Can I calculate my age in months, weeks, or days?
Yes. The calculator provides your calendar age in years, months, and days and also gives total time measurements such as days, weeks, hours, minutes, and seconds.