Context Window Fit Checker
Paste text, or pick a preset like "an entire novel," to see whether it fits inside current AI model context windows — and how much room is left over for a response.
Context windows last verified 2026-08-07.
0 estimated tokens
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What "fits" actually means in practice
A context window is a hard technical limit — content beyond it simply won't be included in the request. But fitting is a necessary condition for the model to use information well, not a sufficient one: several evaluations have found that recall accuracy for facts buried deep in a long context can be noticeably worse than for facts near the beginning or end, a pattern often called "lost in the middle." For a task where precise recall from deep in a long document matters, it's worth testing directly rather than assuming a technical fit guarantees a good result.
Frequently asked questions
Why would something 'fit' but the model still struggle with it?
Several independent evaluations have found that model accuracy can decline well before the stated context limit is reached, particularly for details buried in the middle of a very long input. Technically fitting and being reliably understood aren't quite the same thing for content near the top of a window.
Does the model's response also count against the context window?
Yes — the context window covers everything in a single exchange: your input, any conversation history, and the model's response, all combined. A very long input leaves less room for a long response.
How is word count converted to tokens here?
Using the common approximation of roughly 0.75 words per token in English (or about 4 characters per token), which is the same rule of thumb providers themselves publish. Actual counts vary by content type and language.