Dates

Date and time calculator

Age, business days, date difference, hours worked, time zones, time planning and focus cycles. Leap years and dates that do not exist are handled by the real calendar; time zones use the zone identifier, not a fixed offset.

7 functionsDates, Times and Productivity

7 functions

Years

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Months

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Days

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Age

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Date of birth

Reference dateoptional

Result

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Age

Function guide

What it does: Calculates the exact age between a birth date and a reference date, in years, months and days.
What it is for: For age on a document, in a registration form and in any assessment that works with age bands.
When to use it: Use it when the birth date is known and the reference matters: age on a future date is not today's age.
What to fill in: Birth date and, optionally, the reference date — without it the calculation uses today.
Formula: Years, months and days are counted on the real calendar, not with a 30-day average. 29 February is respected rather than replaced: someone born on 29 February 2000 turns 26 on 1 March 2026, and one day earlier the result is 25 years, 11 months and 30 days.
What each result means: Years, months and days, the total days lived and the date of the next birthday. A date that does not exist, such as 31 February, is refused.
Worked example: Born on 10 May 1990, on 12 November 2026 the person is 36 years, 6 months and 2 days old, with 13335 days lived; the next birthday falls on 10 May 2027.

Each calculation's assumptions are in the function guide — no constant stays hidden.

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