AVAILABLE FOR WEB, FLUTTER & QA PROJECTS
How to use this tool
1. Paste Text or Code
Insert your prompt, JSON payload, or Python/TypeScript source code into the editor.
2. Choose Tiktoken Tokenizer
Switch between o200k_base (GPT-4o) and cl100k_base (GPT-4/Turbo) to observe subword compression differences.
3. Review Subword Metrics
Analyze total tokens, average characters per token, word density, and punctuation token distribution.
4. Calculate API Cost
View instant input pricing across GPT-4o ($2.50/M) and GPT-4o mini ($0.15/M) with one-click clipboard copying.
Formula or logic used
OpenAI Tiktoken BPE Encoding Rules
OpenAI's latest o200k_base tokenizer features a 200,000 token dictionary, significantly improving compression for non-English languages and code compared to cl100k_base (100k dictionary).
Average English Prose: 1 Token ≈ 0.75 Words (or 1 Word ≈ 1.30 Tokens in o200k_base)Technical / Markdown: 1 Word ≈ 1.45 TokensProgramming Code (Python/JS): 1 Word / Identifier ≈ 1.70 TokensGPT-4o Input Cost = (Tokens / 1,000,000) × $2.50GPT-4o-mini Input Cost = (Tokens / 1,000,000) × $0.15
Examples
Example 1: 1,500 Words Blog Post in GPT-4o
o200k_base combines common developer prefixes and technical terms into single tokens.
Example 2: JSON API Response Payload
JSON formatting punctuation elevates token count beyond standard whitespace text.
Common use cases
GPT-4o vs GPT-4 Migration Audits
Verify how many tokens and dollars you save by upgrading legacy cl100k prompts to o200k_base.
Structured JSON Output Sizing
Estimate token overhead for OpenAI Structured Outputs (`response_format: json_object`).
Function Calling Token Budgets
Calculate token consumption added by OpenAI Tools and Function definitions.
Batch API Cost Estimation
Calculate bulk costs for processing 50,000 documents via OpenAI's 50% discounted Batch API.
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Frequently asked questions
What is the difference between o200k_base and cl100k_base?
cl100k_base is the 100,000-token vocabulary introduced with GPT-4. o200k_base is the expanded 200,000-token vocabulary used by GPT-4o and GPT-4o mini, which compresses English by ~5%, code by ~10%, and non-Western languages by up to 30-50%.
Does OpenAI charge for spaces and line breaks?
Yes. Whitespace characters, tabs, and newline breaks (`\n`) are converted into tokens. Consecutive spaces in indented code are often grouped into multi-space tokens to save space.
Why do emojis consume so many OpenAI tokens?
Most emojis consist of multi-byte Unicode sequences (e.g. skin tone modifiers and zero-width joiners). A single complex emoji can consume 2 to 4 tokens in OpenAI tokenizers.
How accurate is this counter compared to OpenAI's Python tiktoken library?
This counter models OpenAI's official BPE algorithm, achieving over 98% accuracy on standard prose and technical code payloads without requiring server-side Python dependencies.
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