1. Pick your areas
Areas are the broadest buckets, numbered in tens. A personal setup might be 10-19 Life admin, 20-29 Work and 30-39 Hobbies. Create these as folders in Documents. Keep it to a handful; you can add more later.
2. Add categories and IDs
Inside each area, add up to ten categories, then numbered folders inside those as you need them. For example:
10-19 Life admin
11 Finances
11.01 Bank statements
11.02 Invoices and receipts
11.03 Tax
12 Home
12.01 Insurance
12.02 Manuals3. Keep an index
Keep a plain text file called 00.00 Index.txt at the top listing every number and what it's for. Before making a new folder, check the index; it stops duplicates like “Receipts” and “Invoices” creeping in.
4. File new documents automatically
The system only works if files actually reach their numbers. TidyFile rules can route the regular arrivals straight from Downloads: invoices and receipts into 11.02, bank statements into 11.01. Pair it with the PARA method if you prefer four broad folders to numbers.
The TidyFile rule
Receipts to 11.02
- When a file
- in Downloads · name contains invoice, receipt or inv
- Then
- move to Documents\10-19 Life admin\11 Finances\11.02 Invoices and receipts
Tip: folders like Documents or Pictures mean your own folders. In TidyFile, click Browse to pick the folder, then add the rest, such as \{year}. A folder typed without a drive letter is created inside the watched folder instead.
Set it up once and TidyFile applies it in the background, to new files the moment they arrive. Preview what it'll do to the files already there, and undo anything from the activity log.
Questions
What is Johnny Decimal?+
A numbering system for folders, created by Johnny Noble. You get up to ten areas (10–19, 20–29…), up to ten categories inside each (11, 12…), and numbered items inside each category (11.01, 11.02…). Every file has a short address you can remember.
Why only ten categories per area?+
It's deliberate. The limit forces broad, stable categories, so you're not inventing a new folder every week, and it keeps every number two digits.
Does Johnny Decimal work with Windows search?+
Very well. Type an ID like 11.03 into File Explorer's search box and it jumps straight to that folder.