LLM Context Window Comparison 2026 (refreshed): Ranked by Largest Usable Context, Not Advertised Maximum
The 2026 version of “which model has the largest context window” no longer has a single winner among the hosted APIs developers actually call, because those models now advertise the same ~1M-token class: OpenAI’s GPT-4.1 is documented at 1,047,576 tokens, Google’s Gemini 2.5 Pro at 1,048,576 tokens, and Anthropic’s Claude Opus 4.6 at 1M tokens. What still separates them is whether the long window is the default or a beta, how many tokens one response can generate inside that window, and how much of the window your document keeps once system prompts, tool definitions, tool results and the model’s own output are counted against it. Every figure below was read from the vendors’ own documentation on 2026-10-15, and the numbers this refresh could not confirm were withdrawn rather than restated. ...