Free tiktoken calculator online: Exact o200k_base and cl100k_base token counts in your browser via gpt-tokenizer, plus cost estimates and a path to the tiktoken visualizer.
Try it in TokenCalculator
Pick an OpenAI model that maps to o200k or cl100k, paste text, and read Exact token counts. Open the visualizer when you need chip level encode views.
Quick answer
A tiktoken calculator counts tokens with OpenAI’s public BPE encodings such as cl100k_base and o200k_base, the same family OpenAI’s tiktoken library uses in Python. TokenCalculator runs a gpt-tokenizer path in the browser, labels matching counts Exact, and never uploads your prompt for counting.
Use this page when you want numbers. Use the tiktoken visualizer guide and tool when you want colored chips and token ids. Use stop using tiktoken for Claude when someone asks you to encode Anthropic text with tiktoken.
What tiktoken is (and is not)
tiktoken is OpenAI’s widely used tokenizer library. It maps text to token ids for published encodings. It is not a universal LLM tokenizer. Claude, Gemini, and Llama families use different vocabularies. Forcing tiktoken onto those providers produces confident wrong counts.
In the browser, TokenCalculator uses gpt-tokenizer compatible logic for supported OpenAI encodings. Treat that as Exact for those encodings. Treat other provider rows as Approx unless we ship an official browser tokenizer.
o200k_base versus cl100k_base
cl100k_base covers many GPT-3.5 and GPT-4 era chat paths. o200k_base covers many GPT-4o and newer OpenAI chat paths. Counts differ on the same string because the merge tables differ.
Pick the encoding that matches your deployment, not the marketing name on a slide. The o200k vs cl100k guide and the visualizer exist for side by side intuition.
Calculator versus visualizer
The calculator job is: paste text, get a token total, optionally turn tokens into cost. The visualizer job is: see each piece, id, and encoding difference. Start here for budgets. Open the visualizer when debugging why two encodings disagree.
Deep link from model pages when you already know the GPT SKU. That keeps encoding choice aligned with the catalog row.
From tiktoken counts to API cost
Token totals alone do not pay invoices. Open the cost calculator with the same OpenAI model, set output size, and scale by monthly volume. Toggle cache and batch when listed.
For offline Python pipelines, keep using official tiktoken in CI. Use TokenCalculator for interactive paste checks and stakeholder demos without installing Python.
Common mistakes
Avoid these tiktoken traps.
- Running tiktoken on Claude or Gemini prompts and calling it Exact
- Mixing o200k and cl100k when comparing two spreadsheets
- Forgetting special tokens and chat formatting outside the raw string
- Assuming a GitHub gist encoding matches your production model id
Real-world scenarios
A backend engineer compares Python tiktoken counts to TokenCalculator on the same fixture file. Both Exact paths agree within the chosen encoding, which builds trust before a finance review.
A prompt designer watches o200k and cl100k diverge on emoji heavy marketing copy. The visualizer shows the split. The calculator shows the budget impact.
A team asked to “just use tiktoken for Llama” reads the Approx Llama guide instead and switches to Hugging Face AutoTokenizer for release gates.
Step-by-step in TokenCalculator
Open the tokenizer with an OpenAI model tied to the encoding you need. Paste the string. Confirm Exact.
If counts look surprising, open the token visualizer on the same text and compare o200k versus cl100k chips.
For spend, jump to the cost calculator with the same model. For Claude work, stop and use Anthropic count_tokens instead of tiktoken.
Warnings
Exact OpenAI encodings are not Exact Claude, Gemini, or Llama counts. The product labels exist on purpose.
Browser counts still require you to paste chat templates and tool schemas when those ship in production.
Frequently asked questions
What is a tiktoken calculator?
A tool that counts tokens using OpenAI tiktoken style encodings such as cl100k_base and o200k_base. TokenCalculator does that in the browser for supported GPT rows and labels them Exact.
Is TokenCalculator the same as Python tiktoken?
It targets the same encoding family via gpt-tokenizer for supported models. For production pipelines, keep official tiktoken in your language runtime and use TokenCalculator for interactive checks.
o200k or cl100k: which should I pick?
Match the encoding to your model. Many GPT-4o era models use o200k_base. Many older GPT-3.5 and GPT-4 chat paths used cl100k_base. Counts differ on the same string.
Can I use tiktoken for Claude?
No for Exact work. Claude uses a different tokenizer. See the stop using tiktoken for Claude guide and Anthropic’s count_tokens API.
Where is the tiktoken visualizer?
Use the token visualizer tool and the tiktoken visualizer o200k / cl100k guide for chip level encode views.
Does the tiktoken calculator upload my text?
No. Counting for supported OpenAI encodings runs locally in your browser.
How do I estimate cost after a tiktoken count?
Open the cost calculator with the same OpenAI model, set output tokens and monthly volume, then confirm rates on OpenAI’s pricing page for contracts.
Why do two tiktoken calculators disagree?
Different encodings, missing special tokens, or one tool approximating non OpenAI models. Compare encoding names first.
Is gpt-tokenizer related to tiktoken?
gpt-tokenizer is a JavaScript friendly implementation used for OpenAI style encodings in the browser. TokenCalculator uses that path for Exact OpenAI rows.
Related tools
Related guides
- Token visualizer: see colored token pieces
- How LLMs split text into tokens
- tiktoken o200k / cl100k
- Code and emoji tokens
- Exact vs fake boundaries
Sources and references
Official documentation for definitions, counting methods, or rate cards. Confirm critical budgets on the provider page.
Next steps
Use the calculator links above for Exact or Approx counts on your own prompts, then browse related guides and model pages to compare pricing assumptions.