Day of Year Calculator

Choose a date to calculate its ordinal day from 1 to 365 or 366.

Date

—Day of year

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

Ordinal date with reverse day-of-year solve

Convert a calendar date to ordinal day and reverse an ordinal number back to a date while showing days remaining in the year.

DateReverse ordinal

—Day of year

—Days remaining

—Ordinal → date

—Year progress

Ready.

Calendar or duration rule

Ordinal day counts January 1 as day 1.

Leap years shift dates after February by one ordinal day.

Worked check

In a non-leap year, March 1 is day 60; in a leap year it is day 61 because February has an extra day. This makes dates after February a useful sanity check when verifying ordinal-day calculations.

Rule: Ordinal day counts January 1 as day 1. Leap years shift dates after February by one ordinal day. For a final check, distinguish calendar arithmetic from elapsed duration, confirm the intended local date or time zone, and inspect month-end, leap-year or daylight-saving boundaries when they can affect the meaning.

Ordinal-date semantics

January 1 is day 1. Leap years have 366 days and every date after February 28 shifts by one ordinal day compared with a common year.