Calculate calendar age, completed months, elapsed days and the next birthday from explicit dates.
Your inputs stay on your device. All calculations run in your browser without uploading, storing or tracking the numbers you enter. Clear formulas and visible assumptions let you review the estimate.
Complete calendar months are measured from the birth date, clamping anniversaries to the last day of shorter months. Remaining days follow that anniversary.
Gregorian date-only arithmetic for years 0001–9999. February 29 uses February 28 in non-leap years. No time of birth or legal-age rules are inferred.
Decimal arithmetic uses exact fractions. Currency displays round to two decimals; exact unrounded values are included where relevant. Date calculations use whole Gregorian calendar days. Results are estimates under the stated assumptions.
No. Inputs are processed locally and not persisted. Only the theme preference is stored. Copy and report downloads happen when you choose them.
