Age Calculator
Calculate calendar age and the number of days until the next birthday.
Your result
EVERYDAYEnter your values and select calculate.
On this page How it works & practical examples
How to use the Age Calculator
Select the birth date and the date on which age should be measured. The calculation counts calendar anniversaries instead of dividing a day count by 365, since years and months have different lengths. Total days is shown separately. The “age on” field starts with the current date from your device, but can be changed to a past or future date.
The calculation
Worked example
Someone born on June 15, 1990 is exactly 35 years old on June 15, 2025. On June 14, 2025, the next birthday is one day away.
Assumptions and limits
This is a date-only calculation and does not consider time of birth or time zones. February 29 birthdays are treated as February 28 in a non-leap year, and a month anniversary falling past the month’s end is clamped to its final day. Those conventions may differ from legal rules. Birth dates must not follow the selected reference date; dates from 1900 to 9999 are supported.
Common questions
Why not divide days by 365?
Leap years and month lengths make that an approximate elapsed time, rather than a completed calendar age.
Is this suitable for legal eligibility?
Use the applicable legal rule. This page’s leap-day and date-only conventions are stated for ordinary calendar calculations.