Will It Fit? Context Checker

Check if your document fits a model's context window in one call.

Quick answer

With the default inputs, Yes — it fits in one call — 53,000 tokens needed vs 128,000 tokens window. Enter your own numbers below to recompute instantly; the full step-by-step math is shown under the worked example.

Model

Document size(tokens)

Results update automatically as you type.

Result

Yes — it fits in one call

53,000 tokens needed vs 128,000 tokens window

Document: 50,000 tokens
Prompt / instructions: 1,000 tokens
Reserved for output: 2,000 tokens
Total needed: 53,000 tokens
Context window: 128,000 tokens
Docs of this size per call: 2

Pasting a long document into a model? Enter its token size, your prompt and the output you need, then pick a model to see whether it fits in a single call — and how many documents of that size you could fit.

How this is calculated

We add your document, prompt and reserved-output tokens and compare the total to the model's context window. If it fits, we also show how many documents of that size you could include in a single call (window ÷ per-document tokens).

Is this a good result? What to do next

'Fits' is necessary but not sufficient: even when a document technically fits, packing the window can reduce answer quality. If you're close to the limit, chunking with RAG or a larger-context model is usually more reliable than squeezing everything in.

Typical planning ranges

1M-token models (GPT-4.1, Gemini 2.5, Claude 4): fit large documents
~200-page book: ~150k tokens
Reserve for output: subtract before checking fit

Ranges are typical planning figures to sanity-check your result, not authoritative benchmarks. Your numbers will vary with use case, volume, and vendor.

How to improve this number

Reserve enough output tokens before checking fit.
Chunk and retrieve, or summarize sections, when a doc doesn't fit.
Move to a larger-context model for very long inputs.

Common mistakes

Forgetting to reserve space for the model's response.
Assuming a document that fits will also be answered well.

When to use a different approach

To see percentage utilization, use the context window usage calculator. To estimate a PDF's token size and cost, use the PDF token and cost calculator.