How large is the Stacks project and what does it cover?

Updated

The Stacks project is an open-source textbook and reference work on algebraic geometry. As of the statistics shown on its homepage, it contains 7,654 pages, 767,328 lines of code, 21,446 tags, 3,298 sections, 116 chapters, and 244 slogans. That scale makes it less a single book than a structured library: the chapter and section counts show the material is organized into many distinct topics, while the tag count reflects a dense internal cross-referencing system.

What the numbers mean

Statistic Count What it indicates
Pages 7,654 Overall length of the compiled work
Lines of code 767,328 Size of the underlying LaTeX source
Tags 21,446 Number of individually referenceable results, definitions, and remarks
Sections 3,298 Granular topical units within chapters
Chapters 116 Broad subject divisions
Slogans 244 Short informal summaries attached to parts of the text

The tag count is the most telling figure for how the project is used. Each tag is a stable identifier for a specific result or definition, so a reader can cite or look up an exact statement rather than a page number. With over 21,000 tags spread across roughly 3,300 sections, the average section holds several individually addressable items.

What it covers

The project describes itself as covering algebraic geometry broadly, including stacks. The chapter and section structure is the best guide to scope: with 116 chapters, the work spans foundational material through advanced topics rather than concentrating on a single subfield. The presence of stacks in the title and description signals that the theory of algebraic stacks is a core part of the coverage, not an appendix.

Because the table of contents is the authoritative map of the material, the practical way to judge whether a topic is covered is to browse the table of contents or search the site rather than infer from the statistics alone. The statistics tell you the work is large and finely subdivided; the table of contents tells you what is actually inside.

How to use the size to your advantage

  • Start from the table of contents if you want to see the chapter-level scope before committing to reading.
  • Use search or tags if you already know the result you need; a tag gives you a precise, citable location.
  • Check recent changes and the blog if you need to know how current a section is. The homepage lists recent comments, recent commits, and recent blog posts, which show the project is actively edited rather than frozen.

One caveat worth noting: the statistics are a snapshot. The homepage shows recent commits and comments dated into 2026, so the counts will drift as material is added or revised. Treat the figures as an order-of-magnitude description of scale, and confirm specific content through the table of contents or search.