Chronological Age Calculator
Calculate exact chronological age with year, month, day, hour, and minute precision—ideal for contests, school placement, or medical forms.
Leave as 00:00 if time of birth is unknown.
Set to the exact evaluation moment for test or eligibility requirements.
Chronological Age as of November 25, 2025 at 11:49 AM
Exact age
20 year(s), 2 month(s), 10 day(s), 11 hour(s), 49 minute(s)
Total time lived
7,376 days • 177,035 hours • 10,622,149 minutes
20.1962 years • 242.3538 months
How to Use This Calculator
Provide birth details
Enter the date and optionally time of birth. Including time increases accuracy for programs that require exact ages.
Set the evaluation moment
Use the reference date/time for the day you want to measure age (exam day, roster deadline, etc.).
Review precise results
The calculator outputs years, months, days, and smaller units so you can confirm eligibility or prepare documentation.
Formula
Milliseconds = Reference − Birth
Total Days = Milliseconds ÷ 86,400,000
Year/Month/Day components = Calendar subtraction with borrow
Decimal Years = Milliseconds ÷ (365.2425 × 86,400,000)
Example: Born 2005-09-15 08:30, evaluated 2025-11-09 12:00 → 20 years, 1 month, 25 days, 3 hours, 30 minutes • 7365.1 days.
When Precise Age Matters
Use chronological age calculations for school grade placement, athletic competitions, legal age verification, and medical dosing guidelines.
- Confirm eligibility windows that require being “under 12 years old” on a specific date.
- Document age for immigration, adoption, or scholarship applications.
- Measure developmental milestones relative to exact months.
- Coordinate age-sensitive events like quinceañeras or bar/bat mitzvahs.
Frequently Asked Questions
What if I don’t know the birth time?
Leave the birth time at 00:00 or noon. The calculator will still provide accurate day-level results.
Does time zone matter?
It uses the local time zone of your device for both inputs. For official documents, convert all times to the same zone first.
Can I get age in hours only?
The total hours and minutes fields provide exactly that—copy them for forms or spreadsheets.
Is decimal age legally recognized?
Most regulations use whole years or days. Decimal years are helpful for precise comparisons but always confirm governing rules.