Age Calculator
Calculate age in years, months and days, total days lived and the next birthday from two calendar dates.
Set your values
Adjust the values, then calculate your result.
How to use Age Calculator
- Enter your values or reset the included example.
- Review the settings and the format notes before continuing.
- Select Calculate, then inspect or copy the result.
Calculate a calendar age rather than dividing days
Enter a birth date and optionally a reference date. Leaving the reference date empty uses today in your browser’s local calendar. The result separates completed years, completed additional months and remaining days, then gives the total elapsed day count and the next birthday. This is more informative than dividing days by three hundred sixty-five, which ignores leap years and the varying lengths of months.
Understand the date convention
All calculations compare calendar dates without time-of-day or daylight-saving offsets. Month-end anniversaries are clamped to the final valid day of the destination month. A February twenty-ninth birthday is treated as February twenty-eighth in a non-leap year for this tool. Legal birthday and eligibility rules can differ, so the result is not an official age determination. Birth and reference dates must be valid and fall between nineteen hundred and twenty-one ninety-nine.
Where is my calculation performed?
The calculation runs locally in your browser without a conversion API request.
Is input uploaded?
Processing takes place in your browser. This tool does not send your input or selected files to a conversion API.