What are tokens in AI language models?
Tokens are the basic units that LLMs use to process text. A token can be a word, part of a word, or a punctuation mark. In English, one token is roughly 4 characters or 0.75 words. For example, 'chatbot' is one token, while 'understanding' might be split into 'under' + 'standing'.
How many tokens can GPT-4 and Claude handle?
GPT-4o supports up to 128K tokens context window. Claude 3.5 Sonnet supports 200K tokens. GPT-4 Turbo supports 128K tokens. These limits include both input (prompt) and output (response) tokens combined.
How are AI API costs calculated based on tokens?
AI APIs charge per token, usually priced per 1 million tokens. Input tokens (your prompt) and output tokens (the response) are priced differently, with output tokens typically costing 3-5x more. This tool shows both input and output costs for each model.
Is the token count exact for all models?
The count is an approximation based on the average of ~4 characters per token for English text. Each model uses its own tokenizer (GPT uses tiktoken, Claude uses its own BPE tokenizer), so exact counts may vary slightly. The estimate is accurate enough for cost planning.
How can I reduce token usage to lower API costs?
Remove unnecessary whitespace and verbose instructions. Use concise prompts. Avoid repeating context. Use system messages efficiently. Consider shorter model responses by setting max_tokens. For large documents, use chunking or summarization before sending to the API.
Do different languages use different amounts of tokens?
Yes. English is the most token-efficient language for most LLMs. Chinese, Japanese, Korean, and other non-Latin languages typically require 2-3x more tokens per word because the tokenizers were primarily trained on English text. This significantly affects API costs for non-English use.
What is a context window in AI models?
The context window is the maximum number of tokens an AI model can process in a single request, including both the input prompt and the generated output. If your text exceeds the context window, it will be truncated or the API will return an error.
Does this tool send my text to any AI service?
No. Token counting is performed entirely in your browser using a local approximation algorithm. Your text is never sent to OpenAI, Anthropic, Google, or any other service.