Method
How the age in days calculator works
Both dates are normalized to UTC calendar midnights and their difference is divided by 86,400,000 milliseconds. The remaining units are derived from that day count.
Counting clock time within a day rather than calendar days? The hours calculator measures the hours and minutes between two times, the time card calculator totals a week of shifts, the add time calculator adds or subtracts durations, and the military time converter switches between 24-hour and AM/PM times. The rest are in the time calculators collection.
Example
Age in days calculator example
A person born on 15 June 1990 has lived 13,228 days by 2 September 2026, which is about 1,889 weeks.
FAQ
Age in days calculator FAQ
Why is the year figure approximate?
Years are derived by dividing days by 365.25 to average leap years. Use the age calculator for exact completed years, months and days.
Does this include the current day?
No. It counts whole elapsed days between the two calendar dates.
Can I count to a past date?
Yes. Change the second date to any date on or after the date of birth.