Date & Time

Date Calculator

Choose a date and interval for date arithmetic, or switch to date difference when you need elapsed calendar time between two dates.

Starting date

Direction

Amount

Unit

Mixed interval & calendar rules

Years

Months

Weeks

Days

Weeks / days count as

Month-end behavior

Resulting date

—

Ready

—ISO date

—Calendar-day shift

—ISO week

Core timing workflows

Start with a direct timer, stopwatch, alarm or focus workflow. Calendar, date arithmetic, clocks and scheduling specialists remain available from the full Date & Time hub.

All 76 date & time tools

Online TimerCountdown, sound, repeat & fullscreen StopwatchLaps, precision & fullscreen Countdown TimerFocused countdown workflow Alarm ClockAlarm at a local clock time PomodoroFocus and break cycles Interval TimerWork/rest rounds Presentation TimerTalk timing with warnings Classroom TimerProjector-friendly countdown

Simple date arithmetic first

Choose a starting date, add or subtract, then enter one amount and unit. The resulting date appears immediately. Open Mixed interval & calendar rules only when you need several units at once, weekday-only counting, or a specific month-end rule.

Date difference

Switch to Difference between dates to compare two calendar dates. Date-only arithmetic avoids time-of-day and daylight-saving shifts.

Date arithmetic uses calendar rules

Days and weeks can be counted as fixed calendar-day intervals, while adding months or years has to account for real month lengths and leap years. The advanced controls let you choose how end-of-month cases are handled instead of silently treating every month as the same number of days.

Date difference is a different question

Use the difference mode when the goal is elapsed time between two dates rather than moving one date forward or backward.

Day counter Business days Months between dates Years between dates