How your exact age is worked out
Enter a date of birth and your age appears straight away. Leave the second date blank for your age today, or pick another date to see how old you were, or will be, on that day.
Years go up by one on each birthday. Whole months are counted from your last birthday, then the days left over. Weeks and days are exact counts of calendar days between the two dates.
Worked example: born March 14, 1992
Take a date of birth of March 14, 1992 and work out the age on November 9, 2026. The last birthday was March 14, 2026, at 34. October 14 is 7 whole months after that, and November 9 is 26 days after October 14. The calculator shows 34 years, 7 months, 26 days.
The same span is 415 months, or 1,808 weeks plus 2 days, or 12,658 days in all. The next birthday is March 14, 2027, in 125 days, at age 35. March 14, 1992 was a Saturday.
When months have different lengths
Months run from 28 to 31 days, which is why age calculators sometimes disagree on months and days. This one moves forward a month at a time, keeping the day of the month. When that day doesn't exist, it uses the last day of the month instead, so one month after January 31 is February 28, or February 29 in a leap year.
That makes someone born on January 31, 2025 exactly 1 month and 1 day old on March 1, 2025. The totals in weeks and days never depend on this rule.
Birthdays on February 29
A leap day birthday only appears on the calendar in leap years. In other years this calculator counts it on February 28, so you turn a year older on the last day of February. Laws differ. Some places treat March 1 as the legal birthday in those years, which can matter for legal ages such as driving or voting.
Other ways to use it
The tool measures the time between any two dates, not only from a birth.
- Put a wedding or start date first to see how long you have been married or in a job.
- Put a future date second to find your age at graduation or retirement.
- Use age in months for babies, whose milestones are usually tracked that way.
- Use age in days to spot milestones such as your 10,000th day.