One page: income at the top, every category below, a Ready to assign line that should end at zero. Printable PDF and a spreadsheet version with the formulas already in (Google Sheets, Excel or Numbers). It is the same layout Budgetfold uses, so if you outgrow paper the numbers move over in a minute.
Download the spreadsheet (.xlsx)
The spreadsheet has the formulas in: a Transactions tab fills Spent, Left turns red when overspent, Ready to assign is computed. Opens in Google Sheets (upload it to Drive), Excel, Numbers or LibreOffice.
A percentage budget tells you what you should spend. A zero-based budget tells you what you can spend, because every dollar you have is already assigned somewhere. When a category runs out, the decision is explicit: move money from another envelope or stop. That friction is the whole point, and it is why the method works for people who have tried everything else.
Budgetfold