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Everyday math

Age Calculator

Exact age in years, months and days, plus total days lived and a countdown to the next birthday, leap-year birthdays handled properly.

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Quick answer

Age counts completed calendar years, months and days, not day-count ÷ 365, which drifts by leap years. Born 29 February? Your birthday is observed on 28 February in non-leap years, the convention official forms use.

Defaults to today.

Age
31y 4m 2d
Total months
376
Total weeks
1,635
Total days
11,447
Next birthday
in 241 days
Tuesday, 15 June 2027

Formulas last verified 2026-10-10. Results are estimates, not financial advice. How we calculate.

Why age is counting, not division

"Years, months, days" is a calendar walk: step forward from the birth date in whole years while they fit, then whole months, then days. Each step respects real month lengths, a month after 31 January is 28 February (clamped), not an imaginary 31 February. Division by 365.25 approximates this; counting is exact, and exactness is the entire point when a form, a cutoff or a milestone hangs on the answer.

Worked example

Born 15 May 1990, on 17 August 2026: last birthday 15 May 2026 → 36 years; 15 May → 15 August → 3 months; 15 → 17 August → 2 days. Total days: 13,243. Next birthday: 15 May 2027, 271 days away.

Where exact age actually matters

  • School admission cutoffs, "5 years as on 1 June" rules are day-precise, and appeals hinge on this arithmetic.
  • Exam eligibility windows, recruitment notifications set minimum and maximum ages on a reference date; a day out is a rejected application.
  • Insurance and pensions, premiums step at exact ages, and some products use "age nearest birthday", which flips six months early. Know which convention your insurer uses.
  • Visas and passports, child fees, adult status and validity periods switch on precise birthdays.

The leap-year footnote that decides real cases

About one person in 1,461 is born on 29 February, and every rule above still needs an answer for them in the three years out of four when the date does not exist. The observed-on-28-February convention (used here) is the common administrative choice; a minority of legal systems say 1 March. The calculator also finds the next real 29 February for the birthday countdown, a leap-day child turning "seven" in birthdays may be 28 in years.

Related date tools

For the gap between any two dates, projects, pregnancies, deadlines, use days between dates, which also counts business days. For "what date is 90 days from now" (notice periods, visa windows, payment terms), the days from today calculator answers with the weekday named.

Frequently asked questions

How is exact age calculated?

By calendar counting: whole years completed at your last birthday, then whole months since it, then leftover days, borrowing from real month lengths, not an average. Dividing total days by 365 drifts because of leap years; calendar counting is what official forms, HR systems and this calculator use.

When does my age change if I was born on 29 February?

In leap years, on the real 29 February. In other years, this calculator, like most official conventions, observes the birthday on 28 February, so the age increments then. A few jurisdictions use 1 March for specific legal purposes; if a legal threshold hangs on the exact day, check the rule that applies to you.

Why do two age calculators disagree by a day?

Two legitimate conventions differ at the edges: how month-end births roll into shorter months (31 January + 1 month), and whether the birthday itself counts as completed. This calculator uses the clamped-month convention (matching timeanddate.com) and increments age on the birthday, with 0 days to the next birthday that day.

How many days old am I?

The total-days figure above counts actual calendar days including every leap day, it is the birth date to today as one subtraction on the calendar. A 30-year-old has lived roughly 10,957 days; the exact figure depends on how many 29 Februaries the span crossed (7 or 8).

Why does the calculator refuse future birth dates?

Age is elapsed time, so a birth date after the "age on" date has no meaning, it is almost always a typo (the two fields swapped, or the wrong year picked). Refusing loudly beats returning a negative age quietly; swap the dates and the result appears.

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