Age CalculatorFree online other calculator — instant results, no sign-up

Age = Y_diff years, M_diff months, D_diff days; Total Days = (Date_target − Date_birth) / 86,400,000 ms; Total Months = (Y_diff × 12) + M_diff; Total Weeks = floor(Total Days / 7); Total Hours = Total Days × 24

• Date_birthThe starting birth date timestamp
• Date_targetThe target evaluation date timestamp
• Y_diffCompleted calendar years between dates after day and month borrowing
• M_diffCompleted calendar months remaining after full years
• D_diffCompleted calendar days remaining after full months
• Total DaysAbsolute number of 24-hour calendar days elapsed between the two dates

The calculation determines completed calendar units by subtracting the birth year, month, and day from the target date, borrowing days from the preceding month and months from the preceding year when the end day or month is smaller than the start. Total days are derived directly from the millisecond difference across calendar dates, with weeks, months, and hours computed from the total day count and full month intervals.

These are the calculator's starting values and the results it actually produces for them.

1. 1Subtract the birth day, month, and year from the target date, adjusting for varying month lengths and leap years via calendar borrowing.
2. 2Express the primary result as completed full years, remaining full months, and remaining days.
3. 3Calculate the absolute elapsed span in days by finding the timestamp difference divided by 86,400,000 milliseconds.
4. 4Compute total whole months, total integer weeks (days divided by 7), and total hours (days multiplied by 24).

Further reading

• timeanddate