Context Window Checker
Check if your text fits within the context window of popular AI models. Paste your prompt and see which models can handle it.
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How to use this calculator
Tokens are estimated at 1 token per 4 characters. The reserved output buffer is subtracted from each model's context window to determine if your input will fit while leaving room for the response.
- 1
Paste your full prompt or document text into the text area.
- 2
Set the number of tokens you want to reserve for the model's output (default: 2,000).
- 3
Read the table to see which models can handle your input and what percentage of each context window you are using.
Frequently asked questions
What does "reserve tokens for output" mean?
The context window is shared between your input and the model's response. If your prompt uses 95% of the window, the model can only generate a very short reply. Reserving tokens (e.g., 2,000) ensures there is space for a meaningful response.
Why does Llama 3 (70B) have a small context window?
The 8,192-token figure reflects the base Llama 3 release. Some fine-tuned or quantized variants support larger windows. Check the specific model card for the deployment you are using, as context limits vary widely by provider and configuration.
Is token estimation accurate for non-English text?
The 4-characters-per-token estimate is calibrated for English. Languages with non-Latin scripts (Chinese, Japanese, Arabic, etc.) often require 1–2 tokens per character, meaning the same number of characters produces far more tokens. For non-English content, assume your token count could be 2–4× higher.
Context Window Checker — See Which AI Models Fit Your Prompt
How to use the context window
Use this context window to heck if your text fits within the context window of popular ai models. Enter your values above and get your result in seconds. The tool is free, works on all devices, and keeps your data private — nothing is stored or shared.
How the context window works
The context window checker uses standard formulas used in AI development, LLM usage planning, and prompt budgeting. Enter your inputs, and the tool calculates the result instantly in your browser. No server-side processing means your data stays on your device. Results update in real time as you change inputs.
Why context window size matters
Every AI model has a maximum context window — the total number of tokens it can process in a single request. Exceed it and the API returns an error or silently truncates your input. Knowing which models can handle your content before making an API call saves debugging time and prevents silent data loss in production applications.
Comparing model context windows in 2024
Context window sizes span three orders of magnitude across popular models. Llama 3's base models top out at 8,192 tokens — enough for a few pages. GPT-4 Turbo and Claude 3 extend to 128,000–200,000 tokens, covering books and long codebases. Gemini 1.5 Pro's 1,000,000-token window is the current public frontier, capable of processing entire novels or large codebases in a single call.
Context window: how it works
This free tool saves time and reduces the chance of manual errors. Enter your values, get an instant result, and use it as a starting point for further analysis or professional consultation.
Who uses this tool?
Anyone who needs a fast, reliable answer uses this tool as a first step. It is designed to be accessible to non-specialists while accurate enough to trust for most everyday purposes.
Learn more from an authoritative source:
OpenAI Platform DocsAI Token Counter
Estimate the number of tokens in your text for GPT-4, Claude, Gemini, and other LLMs. Useful for staying within context limits.
AI Prompt Cost Calculator
Calculate the cost of an AI API call based on input/output tokens and model pricing.
Words to Tokens Converter
Convert between words, characters, tokens, and pages for AI models and content planning.
AI API Budget Calculator
Plan your monthly AI API budget based on usage volume, model selection, and request patterns.
Results are estimates for informational purposes only and do not constitute professional financial, medical, legal, or technical advice. Read full disclaimer →