Day of year to date converter
Helps you read ordinal dates printed on products or in logs, such as day 256 of the year.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter year and day number.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Date = 1 January of the year + (day number − 1) days.
Example
Inputs: Year = 2,026, Day number = 256. Result: Date: Sunday, September 13, 2026 (2026-09-13); Day of the week: Sunday; Days left in the year: 109.
Limits and caveats
- Assumes 1 January is day 1; some technical systems count from 0.
Questions about this tool
What date is day 256?
It is 13 September in a common year and 12 September in a leap year.
Why is day 366 rejected?
It exists only in leap years such as 2024 and 2028.
How do I read a code like 26274 on a product?
It often means year 2026, day 274, so enter 2026 and 274. Check the maker's guide since formats vary.