Find your age in completed years and total elapsed days between two dates.
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Completed age is the difference between the calendar years, minus one if the birthday has not yet occurred in the reference year. The calculator also reports elapsed days between the birth date and reference date.
Formula · Worked example · Units and assumptions · Questions and answers
Age = completed calendar years between the birth date and reference dateSomeone born on January 1, 2000 is 25 completed years old on January 1, 2025.
Subtracting the birth year without checking the month and day. The reference date must be on or after the birth date.
Explanations updated . See the calculation methodology for precision and review details.
Use the matching example buttons in the calculator to load these inputs. The scenarios are illustrative, not personal advice or real customer records.
Result: 24 years
The birthday has not yet occurred in the reference year, so simple year subtraction would overstate completed age. Use the exact reference date when checking a historical record.
Result: 24 years
This tool advances a February 29 birthday on March 1 in a non-leap year. The example demonstrates the implementation, not a legal-age ruling; local rules may differ.
Worked decisions, assumptions, and checks that put the tools in context. Guides are currently published in English.
Choose between elapsed days, inclusive calendar dates, signed countdowns, and completed age with leap-year examples and clearly defined calendar rules.
Read the guide →A birthday must have occurred in the reference year before another completed year is counted.
Yes. It compares actual calendar dates and uses UTC day boundaries for total elapsed days.
No. The calculation runs in your browser and the entered dates are not sent to our server.