Calculate exact age in years, months and days between two calendar dates.
UNDERSTAND THE ANSWER
How is this calculated?
The calculator counts completed calendar years first, then completed months, then remaining days. It also reports total elapsed days and the next birthday.
Calendar age calculationAge = Full years + full months + remaining calendar days
A practical example
Someone born January 15, 2000 is 25 years, 2 months and 5 days old on March 20, 2025.
Assumptions, interpretation and common mistakes
Calculation assumptions
Both inputs are valid Gregorian calendar dates.
Age is measured at UTC midnight without a time-of-day component.
Leap-day anniversaries are clamped to the last valid day of February when necessary.
How to interpret the result
Full years counts completed birthdays.
Months and days describe the time since the most recent birthday.
Total days is an elapsed-day count and is not divided by an average year length.
Common mistakes to avoid
Estimating age by subtracting birth years without checking the birthday.
Assuming every month has the same number of days.
Using a future birth date or an unintended age-on date.