Date Input
Calendar age is calculated using complete years and months. February 29 anniversaries are clamped to the last valid day of February in non-leap years.
Age Analysis
Birthday-year progress
Date of Birth Calculator
Use this date of birth calculator to find your exact age in years, months and days. Enter a birth date and choose the date on which you want to calculate age. The DOB calculator also shows total days lived, completed weeks and months, birth weekday, next birthday date, birthday countdown and age on the next birthday.
The tool performs calendar-based calculations directly in your browser. It works for current age, age on a past date and age on a future date, provided the calculation date is not earlier than the date of birth.
How to Use the DOB Calculator
- Select your complete date of birth.
- Choose the date on which age should be calculated, or select Use Today.
- Select Calculate Age to refresh the results.
- Review exact calendar age, total days, weeks, months and birthday information.
- Use Copy Results when you need a plain-text age summary.
How exact age is calculated
The calculator first finds the number of complete calendar months between the two dates. It converts those months into complete years and remaining months, then counts the days after the last completed month. This avoids treating every month as a fixed number of days.
What the Results Mean
Exact age
Completed calendar years, remaining complete months and remaining days as of the selected date.
Total days lived
The number of calendar-day boundaries between the birth date and calculation date.
Completed weeks
Total days divided into complete seven-day weeks plus the remaining days.
Completed months
The number of complete calendar months reached since the date of birth.
Next birthday
The next calendar occurrence of the birth month and day, with a countdown from the selected date.
Born weekday
The day of the week on which the selected date of birth occurred.
Age on a Specific Date
An age calculator does not have to use today's date. You can calculate age on a previous date for records and applications, or use a future date to see how old someone will be at an upcoming event. Change the Calculate age on field to the required date.
Because exact age is based on complete calendar units, the result may differ from simply dividing total days by 365. Leap years and months with different lengths are included automatically.
February 29 birthdays
For calculation consistency, a February 29 birthday is matched to the last valid day of February in a non-leap year. Legal birthday rules can differ by country and purpose, so check the applicable official rule when age determines legal eligibility.
Date of Birth Calculator Uses
- Calculate current age from a birth date
- Check age on an application, examination or eligibility date
- Find an upcoming birthday countdown
- Calculate a child's age in years, months and days
- Check the weekday of birth
- Estimate total days, weeks, months and hours lived
- Plan age milestones and birthday events
Frequently Asked Questions
How do I calculate age from date of birth?
Enter the date of birth and the date on which age should be calculated. The calculator returns complete years, months and days.
Can I calculate age on a past date?
Yes. Select any calculation date that is the same as or later than the date of birth.
Can I calculate age on a future date?
Yes. Choose a future calculation date to find the age someone will have on that date.
Does the calculator include leap years?
Yes. Leap days are included automatically in total-day calculations.
How are February 29 birthdays handled?
The calculator uses the final valid day of February as the anniversary in a non-leap year.
Why is exact age different from total days divided by 365?
Calendar years and months have different lengths, and leap years contain an additional day. Exact age uses complete calendar units.
What does completed months mean?
It is the number of full calendar months reached from the date of birth through the selected calculation date.
Are the hours lived exact?
No. Hours are an approximation based on total calendar days multiplied by 24 because birth time and time zone are not entered.
Does the tool save my date of birth?
No. Calculations run in the browser, and the tool does not send or store the entered dates.
Is the zodiac result part of the age calculation?
No. The Western zodiac label is an optional date-based fact and does not affect the calculated age.