---
title: ".one file — what it is and how to open it"
description: "A .one file is an OneNote Section. A section of a OneNote notebook, holding pages of freeform notes. How to open one on Windows, macOS and Linux, and what to convert it to."
url: https://atoneplace.net/file/one/
site: "At One Place"
---

# .one files

**.one file: OneNote Section**

A section of a OneNote notebook, holding pages of freeform notes.

## What opens a .one file

- **Windows:** Microsoft OneNote
- **macOS:** Microsoft OneNote
- **Linux:** OneNote for the web (notebooks in OneDrive only)
- **In a browser:** OneNote for the web

## What a .one file is

A .one file is one section of a OneNote notebook. Modern OneNote keeps notebooks in OneDrive and syncs them, so a loose .one file is usually an old local notebook or a backup. OneNote on Windows and Mac can open it via File > Open Notebook — double-clicking often does nothing useful — and OneNote for the web only reads notebooks that live in OneDrive.

## Converting it

A .one file is commonly converted to .pdf, .docx or .onepkg. It is a binary format, so a text editor will show unreadable characters rather than its contents.

## Details

- **Extension:** .one
- **Full name:** OneNote Section
- **Category:** Documents
- **Created by:** Microsoft
- **Format:** Binary

## Common questions

### How do I open a .one file?

On Windows use Microsoft OneNote; on macOS use Microsoft OneNote; on Linux use OneNote for the web (notebooks in OneDrive only). A section of a OneNote notebook, holding pages of freeform notes.

### What is a .one file?

OneNote Section. A .one file is one section of a OneNote notebook. Modern OneNote keeps notebooks in OneDrive and syncs them, so a loose .one file is usually an old local notebook or a backup.

### Can I convert a .one file?

Yes. It is usually converted to .pdf, .docx or .onepkg, either by exporting from one of the programs listed above or with a format converter.

## Related pages

- [.pdf — Portable Document Format](https://atoneplace.net/file/pdf/)
- [.docx — Word Document (Open XML)](https://atoneplace.net/file/docx/)
- [.xlsx — Excel Workbook (Open XML)](https://atoneplace.net/file/xlsx/)
- [.pptx — PowerPoint Presentation (Open XML)](https://atoneplace.net/file/pptx/)
- [.txt — Plain Text File](https://atoneplace.net/file/txt/)
- [.doc — Word Document (legacy binary)](https://atoneplace.net/file/doc/)
- [.xls — Excel Workbook (legacy binary)](https://atoneplace.net/file/xls/)
- [.ppt — PowerPoint Presentation (legacy binary)](https://atoneplace.net/file/ppt/)
- [.md — Markdown Document](https://atoneplace.net/file/md/)
- [.rtf — Rich Text Format](https://atoneplace.net/file/rtf/)
- [.pages — Apple Pages Document](https://atoneplace.net/file/pages/)
- [.odt — OpenDocument Text](https://atoneplace.net/file/odt/)

## Sources

- Media Types Registry — IANA (https://www.iana.org/assignments/media-types/)
- Official vendor product documentation — At One Place (/about/)