Step 1
Completed years first
The calculator checks whether the birthday has occurred in the reference year. That determines the completed years before any month or day remainder is added.
Methodology
How Age Calculator HQ handles calendar math.
Great calculator UX gets attention, but credible logic earns trust. This page explains the calendar assumptions behind the results so the product feels both premium and dependable.
Step 2
Then months and days
After the completed years are accounted for, the remaining months and days are measured using true month lengths instead of averaged assumptions.
Step 3
Edge cases are explicit
Leap years, February 29, and month-end borrowing all receive dedicated handling so the result stays stable and understandable.
FAQ
Methodology FAQ
How are years, months, and days calculated?
The method counts completed calendar years first, then completed months, then remaining days. This avoids flattening months into fixed day counts and keeps the result aligned with real human-age expectations.
What happens with February 29 birthdays?
In non-leap years the calculator uses February 28 as the birthday boundary for next-birthday logic, while still honoring leap-year month lengths when calculating elapsed age.
Why publish a methodology page at all?
Because trust matters for calculators. A good methodology page helps users understand leap years, month-end behavior, and result interpretation while also strengthening topical depth for search.