Age Calculator

Subtracting birth year from current year gives the wrong answer for roughly half the population on any given day, because it ignores whether the birthday has already happened this year. Someone born in December 1990 is 35 for eleven months of 2026 and 36 only in the last few weeks. Correct age counts completed years: take the year difference, then subtract one if this year's birthday has not yet arrived.

Leap days complicate the edge. A person born on 29 February has a real birthday only every fourth year, and jurisdictions differ on which day the anniversary falls in a common year. Most legal systems, including India and the UK, treat 1 March as the day the person attains the next age; a few treat 28 February as the anniversary. The difference is one day and it occasionally matters for eligibility cut-offs.

An age broken into years, months and days is not a single number in three units; it is a calendar walk. The calculation takes whole years first, then whole months from the last birthday, then the leftover days. Because months are different lengths, the day component behaves in ways a decimal age never would: the same gap can be reported as 1 month 2 days or 1 month 0 days depending on which months it spans.

This is the source of most disagreements between two age calculators. Counting from 31 January to 28 February can be described as 28 days or as one month, and both are defensible. When an exact figure matters, such as a paediatric dosing chart or a school admission cut-off, use the total-days figure rather than the years-months-days breakdown, because total days is unambiguous.

Several everyday processes hinge on an age computed to the day rather than the year. School admission in India works to a cut-off date, commonly 31 March or 1 June depending on the state and board, and a child born days either side of it enters a different year group. Competitive exam eligibility, including UPSC, SSC, and most state services, is stated as an age band on a specific reference date, not on the exam date. Government scheme eligibility, retirement dates, and insurance premium bands all step at exact ages.

Two practical cautions. Insurance underwriting in India frequently uses age-nearest-birthday rather than age-last-birthday, which makes a policy bought a month before a birthday cheaper than one bought a month after. And any age used for a legal or financial purpose should be computed against the local date at the relevant place, since a birth recorded late at night in one time zone falls on the previous day in another.