Calculate your exact age in years, months, days, hours, minutes, and seconds with our free online Age Calculator. This precise tool accounts for leap years and varying month lengths to provide accurate age calculations for legal documents, school admissions, healthcare records, or personal knowledge.
Unlike a simple subtraction of years, an exact age must roll over correctly at month and day boundaries — and handle the awkward cases like a February 29 birthday. This calculator does that arithmetic for any target date, past or future. To work with raw timestamps instead, try the Milliseconds to Date converter.
A leap-day birth date is the hardest case; the calculator handles it correctly by rolling to March 1 in non-leap years:
Date of birth: 2000-02-29
Target date: 2026-07-0426 years, 4 months, 5 days
(Leap-day birth date handled correctly)An exact age is the elapsed time between two dates expressed as years, months, and days — not just the difference in year numbers. Someone born on 15 March 2000 is not "26" until 15 March 2026; before that they are 25. Computing this correctly means counting whole years, then whole months from the birth day-of-month, then the remaining days, while respecting that months have 28, 29, 30, or 31 days.
Leap years add a wrinkle. A year is a leap year if it is divisible by 4, except century years which must also be divisible by 400 — so 2000 was a leap year but 1900 was not. February 29 birthdays only occur in leap years; in a non-leap year the age rolls over on March 1 instead. The calculator handles this and the varying month lengths automatically, so the result matches what a human would count on a calendar.
Exact age matters for legal eligibility (voting, driving, retirement), school and sports admission cut-offs, healthcare, and contracts. It is also useful for counting the precise span between any two events — a project duration, a warranty period, or time since a milestone. For epoch-based arithmetic on raw timestamps, see the Date to Milliseconds and Current Date and Time tools.