Age Calculator
Enter a past date of birth. The calculator instantly shows your exact age in years, months, and days, plus the total number of days you have been alive.
Updated ·Sources verified
It shows your exact age in completed years, months, and days, plus the total number of days since birth.
Enter your date of birth to calculate your age.
The result updates as soon as you enter a date. It shows completed years first, then whole months, then the remaining days.
How does it work?
The calculator counts completed years from each anniversary, then completed months, then remaining days. If an anniversary day such as the 31st does not exist in a month, that month's last day counts for the monthly step. The total-days figure is the exact number of elapsed days.
Age calculation
- \text{today}
- Today's date.
- \text{birth date}
- The date of birth.
Someone born on 1990-03-15 is 35 years, 2 months, and 23 days old on 2025-06-07.
Method & sources
Today's date is taken from your device's local clock at page load. Calendar arithmetic is used: a month is complete on the matching day, or on that month's last day when the matching day does not exist. February 29 birthdays have their anniversary on March 1 in non-leap years.
Sources
Where this method comes from — use these references to understand the formula, assumptions, and limits.
- Gregorian calendar: leap-year rules — U.S. Naval Observatory, verified 2026-09-08
How we calculate
- Today's date is taken from your device's local clock at page load.
- Calendar arithmetic is used: a month is complete on the matching day, or on that month's last day when the matching day does not exist.
- February 29 birthdays have their anniversary on March 1 in non-leap years.
- The calculation uses UTC midnight for both dates to avoid time-zone edge cases.
- Only dates of birth in the past are accepted.
Rounding
Years, months, and days are whole numbers derived from calendar arithmetic. The total days figure is the exact integer count of elapsed days.
What the calculator does
It counts from your birth date to today using calendar dates, not fixed-length months. The result is split into completed years, whole months, and remaining days, with the total number of elapsed days alongside it.
How to use it
- Enter your date of birth in the date field.
- Read your exact age in years, months, and days on the right.
- Check the total days figure for a single number spanning your whole life.
- Use the share button to copy a link that reopens the same date.
An example
Someone born on March 15, 1990, is 35 years, 2 months, and 23 days old on June 7, 2025. The total is 12,868 days. The months and days always add up to less than a full year.
When it is useful
Useful any time you need a precise age — for a form, to check an age limit, or simply out of curiosity.
FAQ
- How is age calculated?
- The calculator counts completed years from each anniversary, then complete months, then the remaining days. If a matching day such as the 31st is missing from a month, that month's last day counts for the monthly step.
- What if I was born on February 29?
- In non-leap years, the calculator uses March 1 as the anniversary, because February 29 does not exist in those years.
- Does it use my local time zone?
- Both dates are treated as UTC midnight to avoid edge cases where the date could differ by one day depending on time zone.
- Can I calculate the age of someone else?
- Yes — just enter their date of birth. It is not stored; it is included in a link only if you choose Share.
- Can I share a calculation?
- Yes. Use the share button to copy a link that opens the calculator with the same date of birth pre-filled.
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Embed this calculator
Add this calculator to your own site. The snippet includes the calculator iframe and a small attribution link:
<iframe src="https://wisecalcs.com/embed/en/age-calculator" width="100%" height="520" style="border:0" loading="lazy"></iframe>
<p>Calculator from <a href="https://wisecalcs.com/en/health/age-calculator" rel="nofollow noopener">WiseCalcs</a></p>