Enter a date of birth and calculate age today or on another calendar date. See completed years, months, days, total elapsed time, and the countdown to the next birthday.
Quick answer: Exact age uses calendar years, months, and days rather than simply dividing total days by 365. Leap years, different month lengths, and calendar-date boundaries are handled by the calculation.
Dates are compared as calendar dates. Time of day is not used.
Exact Age
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Enter your date of birth to see the result.
Completed Months
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Completed Weeks
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Total Calendar Days
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Next Birthday
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This calculator provides a calendar-date estimate for general information and planning. It does not establish identity, legal age, eligibility, or an official record. Confirm critical results with the relevant authority or document issuer.
The calculator subtracts the birth date from the selected target date using calendar components. It first finds completed years, then completed months, and finally the remaining days.
Calendar Age: Selected Date − Date of Birth, expressed as completed years, months, and remaining days.
Date Borrowing: If the selected day is earlier than the birth day, the calculation borrows the actual number of days in the previous month.
Total Days: Calculated from UTC calendar dates so daylight-saving clock changes do not add or remove a day.
Total Weeks: Complete seven-day periods plus any remaining calendar days.
Subtracting the birth year from the reference year gives only a preliminary number. Completed age depends on whether the birthday has occurred by the reference date.
For a birth date of October 15, 2000 and a reference date of September 1, 2026, 2026 − 2000 equals 26, but the birthday has not arrived. The production calculation returns 25 completed years.
The exact-age result advances through the real Gregorian calendar. It reports completed years, then completed months, then the remaining calendar days; it does not treat a month as 30 days or a year as 365 days.
The reference date is the date on which you want to know the person's age. The field starts with your local calendar date, and Use Today restores that value.
Use today to see the completed age on the current local calendar date.
Choose a historical reference date to check the age reached by an earlier event, form, or record date.
Choose a future reference date to plan for a birthday, event, or cutoff. The reference date must still be on or after the birth date.
Before the birthday, the new year of age is not complete. On the birthday itself, the year count advances and the next-birthday countdown is zero days.
The production calculation rolls a February 29 birthday anniversary to March 1 when the reference year has no February 29. A different legal or administrative rule may use February 28.
When the day component is negative, the calculation borrows the actual length of each preceding month until the remainder is non-negative. Under this rule, January 31 to March 1 is 29 days in 2023 and 30 days in leap year 2024, not one month and one day.
A birth date equal to the reference date returns zero years, zero months, and zero days. A birth date after the reference date, an impossible calendar date, or a date that cannot produce a complete finite result returns the validation state instead of a partial result.
Each example below calls the same calculation used by the interactive result panel; the displayed values are not hand-computed substitutes.
The June birthday has passed, so 36 full years are complete before the remaining months and days are counted.
The October birthday has not arrived. The completed-year result is therefore 25 rather than the simple year difference of 26.
Repeated borrowing across February keeps every component non-negative and reports the elapsed period under the calculator's existing month-end rule.
This tool performs date arithmetic. It does not interpret the rules attached to an age threshold.
For a decision governed by law, policy, medicine, or an issuing authority, verify both the date and the applicable rule with that authority.
The calculator compares the birth date with the selected reference date. It determines completed calendar years, completed months after those years, and the remaining days, then separately calculates total elapsed days and birthday timing.
The year difference ignores whether the birthday has occurred by the reference date. If it has not, that final year is incomplete and cannot be counted as a completed year of age.
They are completed Gregorian calendar units, not averages converted from total days. Years are counted first, then months, and the remaining calendar days are reported last.
In a year without February 29, this calculator uses March 1 as the birthday anniversary. Legal or administrative rules may use February 28, so confirm the rule when the result affects eligibility.
Yes. Select any supported past or future reference date that is on or after the birth date. Use Today restores the current local calendar date.
The calculator returns its validation state rather than a negative age. Impossible dates and dates that cannot produce a complete finite result are also rejected.
Calendar months have different lengths. When necessary, the production calculation borrows the actual days in preceding months until the day remainder is non-negative, rather than assuming every month contains 30 days.
No. It calculates calendar age only. Laws and program rules can define cutoff dates, leap-day treatment, time of birth, residency, or documentation differently, so consult the responsible authority.
Reviewed against the production calculation logic on August 22, 2026. The calculator covers valid Gregorian dates, completed calendar years and months, remaining days, total days, completed weeks, and days until the next birthday.
It does not account for time of birth, jurisdiction-specific age rules, or official eligibility decisions. Confirm critical results with the relevant authority or record issuer.
Add or subtract days and compare calendar dates.
Convert a date and time between supported time zones.
Calculate daily work time, breaks, overnight shifts, and weekly totals.
Count business days between dates or add and subtract workdays.
