Age calculator.
An exact age in years, months and days — as of today or any date.
How exact age is worked out
Age in whole years is just how many birthdays have passed. The months-and-days remainder is counted by calendar: the calculator subtracts the birth month and day from the target date and, when the day comes out negative, borrows the length of the preceding calendar month — which is why the same gap can read as a slightly different number of days depending on the months involved. By default it measures age as of today, but you can set any target date to find an age on a past or future day — handy for working out how old someone will be at an event, or their age on a specific historical date. The totals in months, weeks and days are exact counts from the birth date. To count a plain gap between two arbitrary dates, use the date calculator.
A worked example
Take a birth date of 15 June 1990 measured on 27 July 2026. The last birthday to pass was 15 June 2026, which makes the age 36 years. From 15 June to 15 July is one month, and from there to 27 July is a further twelve days, giving 36 years, 1 month and 12 days. The same span expressed as flat totals is 13,191 days, or 1,884 complete weeks — figures that are exact counts and do not depend on how you carve up the months.
Why "months" is the awkward unit
Years and days are unambiguous; months are not, because they run from 28 to 31 days. That is why the same elapsed time can be described as one month and 12 days or as 42 days, and why two calculators can disagree slightly on the remainder while agreeing exactly on the total number of days.
The convention used here is calendar-based: subtract the month, then the day, and when the day goes negative borrow the length of the preceding calendar month. It matches how people normally describe age in conversation. If you need an unambiguous figure — for eligibility rules, medical dosing or legal thresholds — use the total in days rather than the months-and-days breakdown.
Leap years and 29 February birthdays
Leap days are handled automatically in the day totals, since the calculator counts real calendar days rather than assuming 365 in a year. Someone born on 29 February is the awkward case: in a non-leap year there is no exact anniversary, and conventions differ by jurisdiction — some treat 1 March as the birthday for legal purposes, others 28 February. If a precise date matters legally, check the rule that applies where you are rather than relying on any calculator.