Age Calculator in Years, Months and Days
This calculator splits your age into exact years, months and days. Below is how that breakdown is worked out, and why it differs from a single decimal number.
Enter your date of birth
How the years–months–days breakdown works
We subtract the date parts in order. If today's day is earlier in the month than your birth day, we borrow days from the previous month — and because months have 28 to 31 days, the exact borrowed amount depends on which month it is.
Worked example: born 20 January 2000, today 18 June 2026. The day (18) is earlier than the birth day (20), so we borrow 31 days from May. That gives 26 years, 4 months and 29 days.
Years–months–days vs decimal age
A decimal age expresses the same span as a single number — about 26.41 years in the example above. The years–months–days format is more precise for everyday use, such as paperwork or a child's exact age, because it does not hide the leftover months and days.
Frequently asked questions
Why isn't my age a whole number of years?
Unless today is exactly your birthday, there are leftover months and days since your last birthday. The breakdown shows those remainders instead of rounding.
How are months counted when they have different lengths?
When days need to be borrowed, the calculator uses the actual length of the relevant month (28–31 days), so the result stays accurate across the whole year.