Why "just subtract the years" isn't quite right
Subtracting birth year from the current year gets close, but it's wrong for anyone whose birthday hasn't happened yet this calendar year — someone born in November is still a year "younger" than that simple subtraction suggests until their birthday actually arrives. This tool checks the full date, not just the year, so it correctly accounts for whether this year's birthday has passed and how many days sit between the months in between.
Where this is actually useful
Beyond settling casual arguments, exact age calculations matter for eligibility cutoffs (school enrollment, age-restricted services, insurance brackets), form fields that want a precise figure rather than "about 30," and any situation where the exact number of days since a date matters — anniversaries, milestones, or countdowns to an age-based deadline.