Age Calculator
Calculate calendar age in years, months and days, total days and the next anniversary using an explicit leap-day convention.
YOUR CALCULATION
Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Find the most recent anniversary, count whole anchored months from it and subtract the remaining calendar days.
Age = completed annual anniversaries + anchored complete months + remaining days
Worked example
From 1990-06-15 to 2026-10-28, age is 36 years, 4 months and 13 days. The next annual anniversary is 2027-06-15.
Assumptions and input details
Gregorian date-only calculation for 1900–2199. No browser current date, time zone, birth time or legal-age rule is inferred. A February 29 anniversary uses your selected nonleap-year convention. Complete months are anchored to the most recent anniversary, clamping its day to month end; the next anniversary is strictly later than the comparison date.
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
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