Enter values and select Calculate to see your result.
Age in Years, Months & Days
Enter a date of birth and a comparison date to calculate a detailed age breakdown.
How to use the Age Calculator
Calculate age in completed years, months and days between a birth date and comparison date.
- Enter date of birth.
- Enter the comparison date.
- Calculate the exact calendar breakdown.
Age Calculator formula
Age uses calendar anniversaries and month lengths rather than dividing total days by 365.
Worked example
Inputs: January 1, 1990 to January 1, 2026.
What to expect: The calendar age is 36 years, 0 months and 0 days.
How to read your result
Calendar age and total days differ because months have different lengths and leap years add days.
Frequently asked questions
Can I use a past comparison date?
Yes. Enter any date on or after birth date.
Does it handle leap years?
Yes. Calendar month and leap-day differences are included.