Pevlika Browser Apps

Context Window Calculator

Will your prompt, documents and history fit a model’s context window?

Runs in your browser — nothing is uploaded

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How to use Context Window Calculator

  1. Enter your values — the unit for each field is shown next to it.
  2. The result updates instantly as you type.
  3. Copy the results, or change inputs to compare scenarios.

Formula & assumptions

Free = context window − (system + tools + documents + history + message + reserved output)

  • Model prices as of 2026-09-30 from the Anthropic, OpenAI and Google pricing pages (standard rates, short prompts). Prices change — check the provider before budgeting.
AI Token CounterCount tokens for GPT, Claude and Gemini, with context usage and cost. Chat Context Usage CalculatorHow many chat turns fit before the context window fills up. Chunk Size CalculatorLargest chunk size that fits your retrieval budget and top-k. Words & Characters to Tokens EstimatorConvert word or character counts to LLM tokens — and back.