Date of Birth Calculator

Enter your date of birth and a reference date (or today's date) to calculate your exact age in years, months, weeks, days, hours, minutes, and seconds. You can also work backwards — enter a target age and a reference date to find the corresponding birth date. Perfect for verifying ages, filling out forms, or satisfying curiosity about time elapsed. Also try the find Baby's Age in Months with Baby Age Calculator.

Results

Age in Years

Total Months

Total Weeks

Total Days

Total Hours

Total Minutes

Days Until Next Birthday

Exact Age

How does the Date of Birth Calculator work?

The calculator takes your date of birth and a reference date (defaulting to today) and computes the exact time elapsed between the two. It breaks down the result into years, months, weeks, days, hours, and minutes, accounting for varying month lengths and leap years. See also our Age Calculator.

Why might my calculated age differ from what I expect?

Age calculation systems vary by culture. This calculator uses the most common Western system, where your age increases by one on each birthday. In some traditional systems, a person is considered age 1 at birth, which would produce a different result.

Can I calculate my age on a future or past date?

Yes — simply change the Reference Date field to any date in the past or future. The calculator will compute your age as of that specific date, which is useful for legal purposes, milestone planning, or historical research.

How are leap years handled in the calculation?

The calculator fully accounts for leap years. February 29th birthdays are recognized correctly, and the extra day in leap years is included in total day and week counts. You might also find our Your Birth Year — Birth Year useful.

What is the difference between 'total days' and the years/months/days breakdown?

Total days is the raw count of calendar days between your birth date and the reference date. The years/months/days breakdown, by contrast, expresses the same duration in human-readable units — for example, 2 years, 3 months, and 12 days remaining after whole years and months are counted.

How is 'days until next birthday' calculated?

The calculator finds your next upcoming birthday from the reference date and counts the number of days remaining. If today is your birthday, it returns 0 (or 365 for the following year depending on the implementation).

Can this calculator determine a birth date from a known age?

While this tool primarily computes age from a birth date, you can work backwards by adjusting the reference date and birth date fields to narrow down when someone of a specific age would have been born.

Is time of birth factored into the calculation?

This calculator works at the day level. Time of birth is not included, so the result reflects the date difference only. For highly precise calculations involving hours and minutes of birth, you would need to supply a full timestamp. Check out our Your Exact Age — How Old Am I as well.