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Convert any date to its day-of-year number (1-366) and back, with ISO week number, leap-year check, and days remaining in the year.
Details
A bidirectional date ↔ ordinal converter. Enter a date to get its day-of-year number (e.g. Feb 1 = day 32), or enter a day number + year to get the calendar date. Each result also shows the ISO 8601 week number, whether the year is a leap year, how many days remain until year-end, and the day of the week. Useful for project tracking ("day 184 of 2026"), habit streaks, and log-file naming.
Execution
Fill in the form, run the tool, and review the result in one place.
Samples
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Tool usage guide
Day of Year Converter changes a calendar date into its ordinal day number from 1 to 366, or converts a day number and year back into a date. Each result includes the ISO 8601 week, leap-year status, days remaining in the year, and weekday.
Background
A project schedule records key events by their position within the year.
Problem
The coordinator needs the ordinal day, ISO week, and remaining days for July 4, 2026.
How to use
Select Date → Day of Year and enter 2026-07-04.
Outcome
The date is day 185 of 365, in ISO week 27, with 180 days remaining; it falls on a Saturday in a non-leap year.
Background
A log uses a year and day number instead of a month-and-day date.
Problem
The analyst needs to identify day 60 of 2024 and verify the leap-year calculation.
How to use
Select Day of Year → Date, enter year 2024, and enter day number 60.
Outcome
Day 60 resolves to February 29, 2024, confirming that 2024 is a leap year.
It is the sequential position of a date within its year, from 1 to 365 or 366.
Yes. Select Day of Year → Date and enter the year and day number.
Yes. It identifies leap years and supports day 366 in a leap year.
The result shows the ISO 8601 week number, leap-year status, days remaining in the year, and weekday.
Day 60 of leap year 2024 is February 29.