FREE BROWSER TOOLAI workflow
AI Context Window Calculator — Plan Your Token Budget
Plan how to divide a model’s context window between input and the response you want to generate. This is a budget calculator: supply token counts from your model’s tokenizer or usage report.
Calculations run in your browser. No account or API key is needed.
Your result
- Input tokens
- 34,000
- Planned total
- 42,000
- Tokens remaining
- 86,000
- Window used
- 32.81%
Fits the stated context budget. Input tokens: 34,000 Planned total: 42,000 Tokens remaining: 86,000 Window used: 32.81%
How to use this tool
Enter the context limit for the exact model and endpoint you use.
Split input tokens across instructions, conversation and reference material without counting anything twice.
Reserve space for output and reasoning, then check the remaining capacity or overflow.
Budget the whole request
Documents and previous messages can consume space that you intended to leave for the answer. With a 128,000-token limit, 34,000 input tokens and an 8,000-token response reserve, the plan uses 42,000 tokens and leaves 86,000 available. The result reports overflow instead of hiding a negative balance.
Know what this check cannot tell you
The calculator does not tokenize text, inspect files or infer model settings. Tool definitions, image token charges and retained reasoning may need to be included in the relevant input field. A request can fit the overall context budget and still exceed a model’s separate output cap or request-size limit.
Common questions
Can I enter character counts instead?
No. Tokenization varies by language, content and model. Obtain token counts from the matching tokenizer or provider.
Does fitting guarantee a good answer?
No. Capacity is only a size check. Keep the material relevant and verify the model’s answer against your sources.