Free online calculator · Date
Age Calculator
Calculate age from a date of birth and a reference date.
Formula • Worked example • Interpretation
Calculate age on a selected date
Age calculations count completed calendar years from a birth date to a chosen reference date.
Calculation method
Completed years = reference year − birth year, minus one if the birthday has not yet occurred in the reference year.
Worked example
Someone born June 15, 2000 is 26 complete years old on October 10, 2026.
What your result means
A person’s age in completed years can differ from the number obtained by dividing elapsed days by 365, particularly near leap years.
Tips for better calculations
Set the reference date explicitly when calculating age on a future exam, event, or application date.
Assumptions and limitations
Different jurisdictions may use special rules for February 29 birthdays. For legal or medical age thresholds, follow the relevant official rules.
SiCalcs tools provide estimates and educational calculations; they do not replace professional financial, medical, tax, or legal advice.