How to use the Age calculator
- Enter your numbers. Fill in date of birth, age on this date.
- Read your results. Results update instantly. The headline shows the age; the breakdown below show the details.
How exact age is calculated
We count full calendar months from your birth date to the target date, then the remaining days. If your birthday falls on a day that doesn’t exist in a given month (like February 29 or the 31st), its anniversary is counted on the first day of the following month.
The method
Age = ⌊months ÷ 12⌋ years, months mod 12, + remaining days
Worked example
With these inputs: date of birth1990-06-15.
The calculator gives a age of 36 years (36 years, 3 months, 27 days). Other results: total months435, total weeks1,895, total days13,268, next birthday in246 days.
What your results mean
Your age is shown in completed years, months and days as of the date you choose. Total days counts every calendar day, including leap days.
Tips
- Change the “as of” date to find your age on any past or future date.
- For February 29 birthdays, non-leap-year anniversaries fall on March 1.
Frequently asked questions
How is age calculated?
By counting completed years since birth, then completed months, then remaining days.
How many days old am I?
Enter your birth date. The calculator shows total days lived.
How do leap years affect age?
Total days includes every February 29. Birthdays on Feb 29 are counted as reached on March 1 in non-leap years.
When do leap-day babies have birthdays?
In non-leap years, this calculator treats March 1 as the birthday. Legal conventions vary by state and purpose.
Does time zone matter?
No. The calculation uses calendar dates only.
Can I calculate age on a future date?
Yes. Set the “age on this date” field.
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