Organize Anything With The Johnny Decimal System
The Johnny Decimal system is a method for organizing digital information into at most 10 numbered areas, each split into at most 10 categories, with every item given a unique ID like 12.03. Because the numbering is fixed and shallow, nothing is ever more than two clicks away, and you can find or file anything by its coordinates. It works across any tool (your file system, cloud drive, email, or notes) and pairs well with the PARA method.
In this article, I will introduce the Johnny Decimal system for organizing digital information.
Introduction
While the LIFT principle provides a clear set of principles to avoid feeling overwhelmed and quickly find what we need, the Johnny decimal system provides a “framework” for better organizing our information.
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As we will see, just like the PARA method, the Johnny Decimal system can be used across tools and platforms, which makes it another excellent tool to add to your information/knowledge management toolbox.
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Note that this content is part of my Obsidian Starter Kit
I also cover it in my courses:
Sebastien DuboisHow the Johnny Decimal system works
The Johnny Decimal system is a simple three-step process to organize information:
- Divide everything you want to organize into 10 areas (at most!)
- Within each area, divide your content into 10 categories (at most!)
- Assign a unique number to each area and category
During the first step, you need to:
- Make sure that every area is really different. You don’t want any overlap between those, although it isn’t always easy (or possible!)
- Choose a unique name for each area
One of the core ideas of this system is to group related information together.
With the Johnny Decimal system, you can create at most 10 areas, each containing at most 10 categories. That’s it. The reason for this limitation is to keep things simple and manageable.
The first step of the process aims to force you to broadly organize your content. The limit on the number of areas is there to force you to keep things simple. The fewer folders you have, the easier it will be to identify and locate (cfr LIFT principle) what you are looking for or want to store.
The second step is key. Categories are where your content actually lives. Each category should hold very specific information/content.
Finally, the last step has multiple purposes:
- First, it makes it easier to identify what you’re looking at, which means that you gain time when going through the structure, either to find or file information. Once you recognize the numbers, you don’t even need to read the names anymore
- Second, it allows you to organize categories logically, rather than alphabetically, which allows you to put what you need most often/what makes more sense on top
- Third, it makes it easy to see where information is NOT supposed to be
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How The Johnny Decimal Numbering System Works
With the Johnny Decimal system, numbers are always structured.
For areas:
- two-digit code
- start at 10
- increase by 10 (e.g., 10, 20, 30, ...)
For categories:
- two-digit code
- start at area number + 1 (e.g. 11 for area 10)
- increase by 1
You may also assign a unique number to each item within a category. If you do, then you should use the following form:
<category identifier>.<item identifier> <name>
Where:
<category identifier>is the two-digit code of the category- a decimal dot separates the category number from the item id
<item identifier>is a two-digit code starting with 01 and increasing by 1 (e.g., 02, 03, 04, ...)<name>is the name of the item
Rules:
- You should not create folders below the categories
- Always use the two digits for consistency, and to help your computer sort things correctly
Advice:
- Use the lower numbers for the most important/relevant/often used information (e.g., 10 for an area you use daily and 90 for an area you only rarely need)
- Keep your area and category names clear and concise
- Create (and maintain!) an index of your areas and categories, as recommended here; especially if you use the system in multiple places. That way you’ll ensure consistency across all of those
Note that you could also use Johnny Decimal numbers for your PKM notes. I personally choose not to, but know that it’s a possibility, as explained here.
Benefits of using the Johnny Decimal system
First and foremost, the Johnny Decimal system brings structure to your information:
This alone is a great reason to use this system. It organizes everything clearly, and consistently.
The system forces you to restrict yourself to a limited number of areas and categories, which helps clearly organize your content without feeling overwhelmed by complexity and depth. As mentioned before, this helps a lot to locate and identify information. As mentioned on the official Website, “nothing is more than two clicks away”. It’s easy to find your way, and hard to get lost.
It makes it easy to tell people where to look for things. Imagine calling your partner to ask for a file. If you use the Johnny Decimal system, then you can easily explain where to go to find what you need.
Using the Johnny Decimal makes it easier to search for specific information. Just type in the coordinates (e.g., 10.01) to find related content.
Given that the Johnny Decimal system uses numbers, we can order everything in the most logical manner. Without this system, we often rely on the alphabet, which makes it much harder to order things logically.
Just like the PARA method and the LIFT principle, the Johnny Decimal system can be used in most tools and on most platforms. You can use it for your file system, your Google Drive, your OneDrive, at work, for your e-mail, in your note-taking tool, etc.
Conclusion
In this article, I've introduced the Johnny Decimal system. It's a simple, but very effective system to organize your information across tools and platforms. You can combine this system with the PARA method to organize just about anything.
That's it for today! ✨
Frequently Asked Questions
What is the Johnny Decimal system?
The Johnny Decimal system is a method for organizing digital information using a simple numbered structure. You split everything into at most 10 areas, divide each area into at most 10 categories, and give each item a unique number like 12.03. The result is that every piece of information has a fixed address, so it is easy to find, easy to file, and never buried in deep folders.
How does the Johnny Decimal system work?
It is a three-step process. First, divide everything into at most 10 areas, numbered 10, 20, 30, and so on. Second, divide each area into at most 10 categories, numbered by adding one to the area number (11, 12, 13...). Third, optionally give each item an ID in the form category.item, such as 12.03. You never create folders below the categories, which keeps the structure shallow and predictable.
What is the difference between Johnny Decimal and PARA?
They solve different problems and work well together. PARA organizes your top level by actionability into four buckets (Projects, Areas, Resources, Archives). Johnny Decimal is a numbering framework that brings consistent structure and unique IDs to whatever sits inside those buckets. I combine both: PARA for the high-level split, Johnny Decimal for numbering the areas and categories underneath.
Can you use the Johnny Decimal system in Obsidian?
Yes. It works well for organizing your folder structure in Obsidian, and it is part of the structure I use in my Obsidian Starter Kit. You can also apply Johnny Decimal numbers to individual notes, though I personally choose not to and rely on tags and links for notes instead. The system is tool-agnostic, so the same numbering works across your file system, cloud drive, and note app.
What are the benefits of the Johnny Decimal system?
It brings clear, consistent structure to your information and keeps it shallow, so nothing is more than about two clicks away. The numbers let you order things logically instead of alphabetically, make it obvious where something belongs (and where it does not), and make it easy to tell someone exactly where to find a file. Because it is tool-agnostic, you can reuse the same structure everywhere.
References
- Official Website: https://johnnydecimal.com
- Official forum: https://forum.johnnydecimal.com
- https://hackaday.com/2019/02/02/hack-your-file-hierarchy-with-johnny-decimal-system-deweys-older-brother/
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