Days Old Calculator
Enter a birth date and optional reference date to see the total days lived plus helpful conversions.
Defaults to today—change to see days as of another moment.
From 1/1/1990 to 1/10/2026
13,158
Day(s) old
Weeks: 1879.71
Approx months: 432.30
Approx years: 36.0246
How to Use This Calculator
Provide a birth date
Enter your birth date or that of anyone you’re researching.
Choose reference date
Use the current date or a historical point in time.
Read the results
See days lived plus approximate weeks, months, and years.
Formula
Days Old = Reference Date − Birth Date (calendar days)
Weeks = Days ÷ 7 • Months ≈ Days ÷ 30.4375 • Years ≈ Days ÷ 365.25
Example: Born 1990-01-01; reference 2025-11-09 → 13,145 days old.
Why Count Days Lived?
- Celebrate unique milestones (1,000 days, 10,000 days, etc.).
- Track infant growth or medical reporting intervals.
- Enhance genealogical research with precise durations.
- Convert age requirements expressed in days (e.g., policies or competitions).
Frequently Asked Questions
Does this include leap years?
Yes—calendar math handles leap years automatically.
Can I ignore the reference date?
Leave it as today to see current age, or adjust to compare against past events.
Is time of day considered?
No—this tool counts whole days. For hour-level precision, use the Age in Hours Calculator.
Can I calculate future days?
Yes—set the reference date in the future to see how many days there will be by then.