Does this account for leap years?

Yes — the calculation uses real calendar dates throughout rather than a fixed 365-day year, so leap years are handled automatically and correctly, as explained above.

Why do I need the total days figure, not just years and months?

Rules that say "within 30 days" mean exactly that, but "within one month" is ambiguous when months vary in length. Use the total days figure whenever a rule or deadline is stated in days rather than months.

Age Calculator

Calculate exact age or the interval between two dates in years, months and days.

Runs entirely in your browser — nothing you enter is uploaded.

Date of birth

Measured on

Defaults to today

Reading the two figures

The years-months-days breakdown is how age is normally stated, but 13,315 days is often the figure you actually need. Where a rule specifies “within 30 days” rather than “within one month”, the day total is unambiguous and the month count is not — because months are not all the same length.

Exact age

36y 5m 13d

Total days13,315

Total weeks1,902

Total hours319,560

Next anniversary in199 days

How this works

The interval is built by taking whole years first, then whole months from the remainder, then the leftover days — the same way people describe age in conversation. This matters because months have different lengths: counting 'one month' from 31 January cannot land on 31 February, so the calculation borrows days from the preceding month's actual length rather than assuming 30. Leap years are handled by using real calendar dates throughout rather than fixed-length approximations.

Assumptions

Both dates are treated as calendar dates in local time, with no time-of-day component.
The end date is exclusive of partial days — an age becomes a full year on the birthday itself.
Time zones and daylight saving transitions are not applied to the day count.

Worked example

Someone born on 15 March 1990, measured on 27 August 2026.

Date of birth: 15 March 1990
Measured on: 27 August 2026
Result: 36 years, 5 months, 12 days

Whole years to 15 March 2026 gives 36. From there to 15 August 2026 is five whole months. The remaining 15 to 27 August is 12 days. In total that is 13,314 days.

How to read the result

The years-months-days breakdown is how age is normally stated, but total days is often the figure you actually need — for eligibility windows, notice periods, or anything where a partial month is ambiguous. Where a rule specifies 'within 30 days' rather than 'within one month', use the day total.

Limitations

Not suitable for legal age determination, where jurisdiction-specific rules on the birthday itself may apply.
Dates before the 1582 Gregorian reform are calculated proleptically and will not match historical records.
Does not account for time zones — a birth recorded in another zone may differ by a day.

Frequently asked questions

Does this account for leap years?: Yes — the calculation uses real calendar dates throughout rather than a fixed 365-day year, so leap years are handled automatically and correctly, as explained above.
Why do I need the total days figure, not just years and months?: Rules that say "within 30 days" mean exactly that, but "within one month" is ambiguous when months vary in length. Use the total days figure whenever a rule or deadline is stated in days rather than months.