Count tokens and estimate API costs for GPT-4o, Claude 3.5, Gemini, Llama and more — instantly, in your browser.
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Model & cost estimate
Expected output tokens
1×
Multiplier of input tokens. 1× means output ≈ same length as your prompt.
Context window usage
0 tokens used128K limit
Cost comparison — your current prompt across all models
What are tokens and why do they matter?
Tokens are the fundamental units that large language models (LLMs) use to read and generate text. When you send a prompt to an AI API, your text is first split into tokens using a tokenizer — then the model processes those tokens one by one to generate a response.
How tokenization works
Modern LLMs use Byte Pair Encoding (BPE) tokenization. Common short words like "the", "is", "a" are usually single tokens. Longer or less common words may be split into 2–4 tokens. Numbers, punctuation, and special characters each consume tokens too. On average, 1 token ≈ 0.75 English words, or roughly 4 characters.
Why token count affects your costs
AI APIs charge per token — separately for input (your prompt + conversation history) and output (the model's response). If you're building an app that processes large documents or runs thousands of API calls per day, even small reductions in token count can translate to significant savings. This tool helps you understand your token usage before you run any API calls.
Tips to reduce token usage
Remove unnecessary filler words and redundant instructions from your system prompt. Use structured formats like JSON or bullet points instead of long prose instructions. Summarize long conversation histories instead of sending the full thread. Choose a smaller model (like GPT-4o mini or Claude 3 Haiku) for tasks that don't require top-tier reasoning.
Frequently asked questions
A token is the basic unit of text that AI language models process. Tokens are not the same as words — a single word can be one or multiple tokens. On average, 1 token equals approximately 0.75 words, or 100 tokens equals roughly 75 words in English.
OpenAI charges separately for input tokens (your prompt) and output tokens (the model's response). For example, GPT-4o charges $2.50 per million input tokens and $10.00 per million output tokens. Costs vary significantly between models — GPT-4o mini is approximately 15× cheaper than GPT-4o.
Approximately 1,333 tokens. The general rule is 1 token ≈ 0.75 English words, so 1,000 words ≈ 1,333 tokens. Code, special characters, and non-English text may tokenize differently and use more tokens per word.
GPT-4o has a context window of 128,000 tokens. Claude 3.5 Sonnet supports 200,000 tokens. Gemini 1.5 Pro supports up to 1,000,000 tokens. The context window includes both your input and the model's output.
This tool uses a BPE approximation that closely matches OpenAI's tiktoken library. Results are highly accurate for English text (within 1–3%). For code, special characters, or non-Latin scripts, results may vary slightly from the official API token count.
This tool supports GPT-4o, GPT-4o mini, GPT-4 Turbo, GPT-3.5 Turbo, Claude 3.5 Sonnet, Claude 3 Opus, Claude 3 Haiku, Gemini 1.5 Pro, Gemini 1.5 Flash, Llama 3 70B, and Mistral Large. Pricing reflects the latest published API rates.