What is a .one file?
Microsoft OneNote Section File · Document · Microsoft · 2003
A .one file is a Microsoft OneNote section: a container of free-form notebook pages with text, ink, images and attachments. Sections live inside a notebook folder alongside a .onetoc2 table of contents.
What is a .one file used for?
OneNote stores each notebook section as its own .one file in the MS-ONESTORE format, a revision-based store that starts with a fixed 16-byte GUID. Pages inside are free-form canvases, which is why nothing else renders them faithfully.
Modern OneNote increasingly keeps notebooks in the cloud, so loose .one files usually come from backups or old local notebooks. OneNote for Windows opens them directly via File > Open.
How to open a .one file
The .one format opens in the following apps, grouped by operating system. If one app does not work, try another from the same list. For a step-by-step walkthrough, see how to open a .one file.
Windows
- Microsoft OneNote
- OneNote for the web (after import)
macOS
- Microsoft OneNote (import)
- OneNote for the web
Linux
- OneNote for the web (after import to OneDrive)
How to convert a .one file
You can convert a .one file to pdf, docx using a conversion tool or the export menu of an app that opens it.
.one file signature (magic bytes)
Programs recognise a .one file by the bytes at the start of the file, not by its name. These are the signatures for OneNote. For a full breakdown, see the OneNote file signature page.
| Hex signature | Offset | Note |
|---|---|---|
| E4 52 5C 7B 8C D8 A7 4D AE B1 53 78 D0 29 96 D3 | 0 | OneNote section GUID |
See the full magic-numbers reference for every format.
Frequently asked questions
What is a .one file?
A .one file is a Microsoft OneNote section: a container of free-form notebook pages with text, ink, images and attachments. Sections live inside a notebook folder alongside a .onetoc2 table of contents.
How do I open a .one file?
In OneNote on Windows use File > Open and pick the file, or place it back in its notebook folder. On other platforms, import the notebook into OneDrive and open it with OneNote for the web.
What is the difference between .one and .onetoc2?
Each .one file is one section of a notebook; the .onetoc2 file is the notebook's table of contents that tells OneNote which sections belong together and in what order.
Can I convert a .one file to PDF or Word?
Yes. Open the section in OneNote and export the section or individual pages to PDF or DOCX from the File menu.
Related formats
Sources
Details on this page were checked against authoritative references: