Precise to the day, not rounded to the year
Work out an exact age from a date of birth, including leap years. Also shows total days lived and the next birthday.
Age in whole years is fine socially and useless on a form. Visa applications, insurance and school enrolment all want the exact figure.
The calculation has to respect calendar reality: months are different lengths and February changes size every fourth year. Approximating with 365 days drifts by a day per leap year.
What this calculator shows
- Age in years, months and days as of today
- Total days lived
- How long until the next birthday
What to keep in mind
- Uses calendar arithmetic including leap years, not a fixed 365-day year.
- Age increments on the birthday itself, following the convention used in most countries.
FAQs
How do you count age across a leap year?
By calendar date, not day count. Someone born on 10 May turns a year older each 10 May regardless of whether 366 or 365 days passed.
Why does my age in days seem higher than expected?
Leap days accumulate. Over 40 years you collect ten extra days that a 365-per-year estimate quietly loses.
What about people born on 29 February?
Most legal systems treat the birthday as 1 March in common years, though some use 28 February. The exact day count here is unaffected.
Does it use my local timezone?
It works from calendar dates, so results do not shift with the clock. Right around midnight a different timezone could differ by a day.
Worked example
Why days matter
Input: Born 29 February
Output: A birthday that only lands on the calendar every four years
Note: Leap-day birthdays are usually treated as 1 March in non-leap years for legal purposes, though jurisdictions differ.