A token is the unit a language model reads, about three-quarters of a word. The pages swirling around you in 3D WebGL hold one million tokens of real text: 3,000 printed pages of Alice in Wonderland, on repeat. This is what a million-token context window holds, and the six-year race—through GPT-6 Astra, Claude Opus 5.5, Gemini 4 Argon, and Kimi K3.1 Pro—that made it real.
The million tokens, laid out as a library: 3,000 pages, 75 across and 40 high. Every model in this story could hold some slice of these shelves in mind. Scroll in.
This is one token: a single word on a single page. Every context window in this story is measured in these.
GPT-3 read 2,048 tokens at a time: the six pages you can see. Anything you said earlier fell out of memory.
The chatbot that reached 100 million users held 4,096 tokens, twelve pages. Long conversations forgot their own beginnings.
32,768 tokens is 98 pages: a novella. For the first time you could hand the model a whole essay and ask questions about it.
Claude jumped to 100,000 tokens, 300 pages, enough to read The Great Gatsby in one pass.
Gemini 1.5 Pro was first to hold every page in view. By October 2026, a million tokens ships across open-weight models (Kimi K3.1 Pro, DeepSeek V4.1 Flash 1017, Qwen 3.8 2.4T, MiniMax M3.1, GLM-5.3) and commercial flagships (Claude Opus 5.5, Sonnet 5.5, Fable 5.1, GPT-6 Astra, Gemini 4 Argon).
Those same pages, stacked in 3D space: a million tokens is about 750,000 words, and the pile stands thirty centimetres tall. A model with this window reads the whole stack at once.
Philosopher's Stone through Order of the Phoenix is about 957,000 tokens: the first five novels in a single prompt, with room left for your question. The King James Bible runs about 1.04 million, just over the 1M line (though inside Kimi K3.1 Pro's 1,048,576 and GPT-6 Astra's 1,050,000 window).
At 150 words a minute, a million tokens transcribes three and a half days of nonstop conversation, or every word from two weeks of full-time meetings.
At about 13 tokens a line, a whole production codebase fits in one window: every file and every test, read together. This is why context size changed how AI writes software.
Every stack of books is a model release; its height is the context window (log scale, each gridline is 10×). Solar Rose→Amber stacks are open weights, Electric Violet→Cyan are closed APIs. For three years the skyline is flat: open or closed, a language model read two to four thousand tokens.
MosaicML's StoryWriter took open weights to 65K in May; Claude hit 100K the same month. By November the closed frontier sat at 128–200K, and Yi-34B carried 200K into the open.
Gemini 1.5 Pro crossed a million in February and doubled it by June. Meanwhile 128K became the everyday default; Llama 3.1 made it standard for open weights.
Qwen2.5-1M matched the million with weights you could download, MiniMax-Text-01 shipped four million the same month, and OpenAI brought 1M tokens to the API with GPT-4.1.
Llama 4 Scout claimed 10,000,000 tokens, a window larger than any public benchmark could fill, while GPT-5 and Grok 4 pushed reasoning over massive multi-file contexts.
In September and October 2026, OpenAI launched GPT-6 Astra (1.05M) and GPT-6.1 Sol, Anthropic shipped Claude Opus 5.5, Sonnet 5.5, and Fable 5.1 (1M, #1 on BenchLM at 86.6), Google released Gemini 4 Argon (1M in/1M out), and xAI shipped Grok 4.7 (500K)—while Kimi K3.1 Pro (Oct 23), DeepSeek-V4.1-Flash-1017 (Oct 17), Qwen 3.8 2.4T, GLM-5.3, and MiniMax M3.1 Flash made 1M open weights faster and 10× cheaper.
Hover any 3D stack in the WebGL skyline for its numbers, or filter to open weights to see how fast the gap closed. Click any model below to focus the skyline on its stack.
In 2020 the frontier model held about six pages in mind. Six years later, an open-weights model you can download claims ten million tokens, a 4,883× expansion of machine memory—and every major October 2026 flagship ships with a 1M+ window.
Kimi K3.1 Pro (Oct 23, 2026), DeepSeek-V4.1-Flash-1017 (Oct 17, 2026), Qwen 3.8 (2.4T A95B), and MiniMax M3.1 Flash are open weights with million-token windows—running alongside Claude Opus 5.5 / Sonnet 5.5, GPT-6 Astra / 6.1 Sol, Gemini 4 Argon, and Grok 4.7.
ALL PRICING & SPECS VERIFIED AS OF OCTOBER 2026 (CLAUDE OPUS 5.5, GPT-6 ASTRA, GEMINI 4 ARGON, GROK 4.7, KIMI K3.1 PRO & DEEPSEEK V4.1 FLASH 1017).