Find Date by Day of the Year

Need to turn day-of-year numbers into full calendar dates? The Find Date by Day of the Year tool lets you enter a year and day number (like 2025 138) and instantly converts it into a proper calendar date (like 2025-05-18). It’s great for working with ordinal date formats in logs, datasets, or software systems.

Paste your input above or import a file below.
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Supported file types: .txt, .csv, .log, .json, .md, .xml, .html
Total items: 0

How to Use:

  1. Enter data in the format YYYY [space] Day one pair per line (e.g., 2024 1, 2025 138).
  2. Or import a .txt or .csv file using the Choose File button.
  3. The tool will convert each line to its proper YYYY-MM-DD date.
  4. Use Copy Output or Export to File to save the results.
  5. Click Clear All to reset the tool.

What Find Date by Day of the Year Tool can do:

This tool takes numeric day-of-year values and finds their exact corresponding date. It handles leap years correctly and can process large batches of values via paste or file import.

Example:

Input:

2024 1
2024 366
2025 138
2000 60

Output:

2024-01-01
2024-12-31
2025-05-18
2000-02-29

Common Use Cases:

Perfect for decoding system logs, scientific data, timestamps, or CSV exports where dates are stored by year and day number. Great for reverse-converting ordinal date formats into standard calendar form.

Useful Tools & Suggestions:

After finding a date from a day number, Find Day of the Week helps place it in context especially handy when planning around weekdays or weekends. And if you’re comparing multiple entries, Find Date Difference quickly shows how far apart they actually are.

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