Editing Tokenization & Context Windows (section)

== The context window: AI's working memory ==

The '''context window''' is the total number of tokens the AI can process at once. Think of it as a whiteboard: everything in your conversation — your messages, the AI's responses, any documents you've uploaded, the system prompt — all has to fit on this whiteboard. When it's full, things start falling off the other end.

Current context window sizes (as of early 2026):

| Model || Context window || Roughly equivalent to

| Claude (Anthropic) || 200K tokens || ~150,000 words — a full novel
| GPT-4o (OpenAI) || 128K tokens || ~96,000 words
| Gemini 1.5 Pro (Google) || 1M+ tokens || ~750,000 words — multiple books

These numbers sound enormous, but they fill up faster than you'd think. A long conversation with back-and-forth responses, a few uploaded documents, and a detailed system prompt can eat through 200K tokens in a working session.