Day of the Year Calculator
Convert any date to its day of the year number (1–365/366), or convert a day number back to a calendar date. Works for both leap and non-leap years.
How to Use
- 1 Choose mode — "Date to Day" to find the day number, or "Day to Date" to find the calendar date
- 2 In Date to Day mode, select a date and click Calculate
- 3 In Day to Date mode, enter a day number and year, then click Calculate
- 4 View the result with remaining days in the year shown
Use Cases
Quickly find out what ordinal day of the year a date corresponds to (e.g., March 15 = day 74).
Given day number 200 of 2024, find the exact calendar date.
Many scheduling and logistics systems use ordinal day numbers — this tool converts between both formats.
Ordinal dates (Julian calendar days) are commonly used in astronomical calculations.
FAQ
Day of the year is the sequential number of a date starting from 1 (January 1) to 365 or 366 (December 31) depending on whether it is a leap year.
Yes — in leap years, February has 29 days, so the year has 366 days total. The calculator accounts for this automatically.
In a regular year the maximum is 365; in a leap year it is 366.
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