Age Calculator
Calculate your exact age in years, months, and days from your birth date. Find out how many days you have been alive.
Years
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Months —
Days —
Total Days Lived —
Extended More scenarios, charts & detailed breakdown ▾
Years
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Extra Months —
Extra Days —
Total Days —
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Years
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Months (remainder) —
Days (remainder) —
Total Days Lived —
Total Hours —
Total Weeks —
Total Months —
Days to Next Birthday —
How to Use This Calculator
- Enter your birth year, birth month, and birth day.
- The "As of" fields default to today's date — leave them or change them to a custom target date.
- Click Calculate to see your age in years, months, days, and total days lived.
Formula
Age = Target Date − Birth Date
The difference is first expressed in complete years, then the remaining months, then the remaining days.
Example
Example: Birth date May 15, 1990 → as of March 18, 2026 = 35 years, 10 months, 3 days (13,087 total days).
Frequently Asked Questions
- Enter your birth year, month, and day, then set the "As of" date (which defaults to today). The calculator subtracts the birth date from the target date and expresses the difference in complete years, remaining months, and remaining days. The algorithm first counts complete calendar years, then counts the additional complete months in the remaining partial year, and finally counts the remaining days. This is more accurate than simply dividing total days by 365.25, because it accounts for the actual calendar month lengths and leap year effects in each specific year range.
- Yes — change the "As of" year, month, and day fields to any past or future date you choose. For example, to find how old someone will be on their next birthday, enter the birthday date and their birth date and the result shows zero years, zero months, zero days. To find a person's exact age at a historical event, enter the event date in the "As of" fields. This is useful for genealogy research, insurance calculations, retirement planning, and determining eligibility for age-restricted activities at a specific future date.
- The result is exact to the day for any date combination. The calculation correctly handles leap years (February 29 birthdays), varying month lengths (28, 29, 30, or 31 days), and all calendar rules. For example, a person born on January 31 does not turn one month older on February 28 in a non-leap year — the calculator handles the borrowing of days from the previous month correctly. The total days lived count is also accurate, as it uses the JavaScript Date object's millisecond-precision difference divided by 86,400,000 ms/day.
- If the birth date entered is after the "As of" date, the calculator shows the time until that date in years, months, and days (as positive values counting forward). For example, entering a birth date of January 1, 2030 with an "As of" date of today shows how far in the future that date is. This is useful for pregnancy countdown calculators, event planning, or determining eligibility dates. The total days result will be a negative number if you set the "As of" date earlier than the birth date, indicating days in the future.
- The calculator works with calendar dates only — it does not consider clock times or time zones. This means it calculates age based on the calendar date, not the precise moment of birth in UTC or local time. For most everyday purposes (driver's license age, school enrollment, birthday celebrations), the calendar date is what matters. For legal or scientific purposes requiring exact age to the minute, you would need to account for the birth time and time zone offset. The total days calculation uses day boundaries at midnight local time.