Age In Years Months And Days Calculator

How to Calculate Your Age in Years, Months, and Days

This is the format used on forms, medical charts, and identity documents. The Age in Years, Months and Days Calculator breaks your elapsed time into three calendar parts instead of one large number.

How the Calculation Works

The tool starts by subtracting the birth date from the reference date field by field:

$$Y = y_r - y_b, \qquad M = m_r - m_b, \qquad D = d_r - d_b$$

If the day value is negative, it borrows the number of days in the preceding month and reduces the month count by one. If the month value is then negative, it borrows 12 months and reduces the year count by one. This handles uneven month lengths correctly.

Worked Example

Use August 25, 1992 as the birth date and May 10, 2023 as the reference date. After borrowing across the shorter day and month values, the result is 30 years, 8 months, and 15 days. The same span equals 11,215 total days, or 368 whole months.

$$30 \text{ years}, \quad 8 \text{ months}, \quad 15 \text{ days}$$

To see the same life as a single decimal number, pair this with the Age in Years Calculator or the Age in Days Calculator.