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Age Calculator
Calculate age in years, months, weeks, days, hours, and minutes.
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How this calculator works
Find your exact age down to the minute with our free chronological age calculator. Input your date of birth to calculate your current age in years, months, and days. The tool also breaks down your age into total weeks, days, hours, and minutes, and shows you how many days remain until your next birthday.
- Method
- Strict ISO date parsing with UTC date-only arithmetic, completed calendar-unit decomposition, and end-of-month clamping
- Source
- NIST date/time definitions and Gregorian leap-year rules
- Last reviewed
- 2026-08-26
Method limitations
- Inputs are Gregorian calendar dates, not timestamps.
- Calendar months have variable lengths.
- Missing month-end days clamp to the final valid day.
- February 29 clamps to February 28 in non-leap years.
- Legal age rules vary by jurisdiction.
Engine-backed example
Calendar age across a leap day: worked example
What is the age on March 1, 2024, for someone born on February 28, 2000?
- Date of birth
- February 28, 2000
- Age at date
- March 1, 2024
Calculated Age24 Years, 0 Months, 2 Days
- Total Days lived
- 8,768
- Total Hours lived
- 210,432
- Days until next birthday
- 364 Days
The completed calendar age is 24 years and 2 days. The total-day count includes Gregorian leap days.
Trust and review
Who created and reviewed this calculator?
- Author
- CalcOS Editorial TeamResponsible for date terminology, examples, assumptions, and jurisdiction-neutral age wording.
- Reviewed by
- CalcOS Scientific ReviewTechnical review of Gregorian leap years, strict date parsing, UTC date-only arithmetic, month-end clamping, total-unit conversion, and engine parity.
- Substantive review date
- 2026-08-26Completed year/month/day decomposition, total weeks/days/hours/minutes, next-birthday countdown, invalid chronology, leap days, month ends, and timezone independence.
Sources
- NIST — Leap Years and Leap Day
- NIST — Leap Seconds FAQs and Gregorian leap-year rule
- NIST FIPS PUB 4-1 — Date and Time Representation Definitions
Assumptions used by this calculator
- Both inputs are valid date-only values in the proleptic Gregorian calendar.
- The age-at date is the same as or later than the birth date.
- Completed years and months clamp a missing month-end day to the final valid day of that month.
- A February 29 birth date uses February 28 as the anniversary in non-leap years for this calculator.
- Total hours and minutes are calendar-day equivalents using 24 hours and 1,440 minutes per date-only day.
- Legal age and leap-day anniversary rules can vary; this is a chronological calendar calculation, not legal advice.
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