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# Context window planner

Split a model context window across prompt sections and an output reserve, then see exactly how many tokens to cut from each section on overflow.

Enter a window and an output reserve to plan the sections.

Output and reasoning tokens come out of the same budget as the prompt on current APIs, so a 200,000-token model given a 198,000-token prompt leaves about 2,000 tokens for the answer. The reserve and the safety margin compete with every section you list, not on top of them. Budgets are whole tokens; on overflow the cut amounts below are exact, not rounded advice. The planner does not tokenize your text, price requests, or know each provider's hidden framing overhead; the safety margin is where you absorb that.
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## More AI tools

- [Context fit](/ai/context-fit)
- [Tokenizer playground](/ai/tokenizer)
- [API cost estimator](/ai/cost-estimator)
[All AI tools](/ai)

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Canonical HTML: https://nutter.tools/ai/context-window-planner
Markdown version: https://nutter.tools/ai/context-window-planner.md
Plain-text version: https://nutter.tools/ai/context-window-planner.txt
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