Dates & time

Decide whether you need dates, clock time, or an instant

Date and time questions look similar but often have different counting rules. A birthday countdown uses named calendar dates. A shift calculation subtracts clock readings and an unpaid break. A time-zone conversion identifies the same instant in two places. Pick the tool that matches that distinction before entering values.

Days between dates returns a signed elapsed difference, with an option to count both endpoints as an absolute date count. Date from days moves a starting date forward or backward by whole calendar days. Work days applies selected weekly rest days and a manually entered holiday list. It does not assume a national holiday calendar or substitute-day policy.

Age counts completed birthdays on a selected reference date and gives additional months and days under a stated month-end convention. Birthday countdown identifies the next anniversary. Both make the handling of February twenty-nine explicit, because a non-leap-year convention can affect the answer. Neither determines a legal age threshold or converts a lunar-calendar birthday.

Hours handles a single shift and optional next-day ending. Time duration accepts full start and end date-time values but treats each day as twenty-four hours. These are clock arithmetic models. If an interval crosses a daylight-saving change, real elapsed time can differ from the apparent change on a local clock.

Time zone converter uses named IANA zones and the rules available in your browser. It reports skipped local times and lets you select the earlier or later occurrence when a clock reading repeats. Always include the date when coordinating across zones, and recheck future events after changes in local civil-time rules.

Day of the week verifies a Gregorian date's weekday. Week number uses ISO Monday-first weeks and displays the associated week-year, which can differ from the calendar year near New Year. All date tools explain their supported range and assumptions. Confirm organizational deadlines, payroll calendars, and other consequential schedules against the relevant official record.