Tools
The tokenizer tax
Claude bills per token. A tokenizer cuts text into tokens a few characters long; Claude’s newer one fits less text into each token.
Price your output Download the data (JSON)
57% more tokens per character in our test battery.
Why price per character
A per-token calculator needs a token count, and the same words turn into a different number of tokens on each tokenizer. We measured what each model was actually billed per character of text it wrote (3.409 characters per output token on Claude Haiku 4.5, 2.172 on average on the newer tokenizer), so you can price words directly.
Why Claude Haiku 4.5 is the baseline: it is the only model in our battery on the previous tokenizer. Anthropic’s pricing page says Claude 4.7 and later models use the newer one.
Why 57% and not about 30%: Anthropic’s pricing page says the newer tokenizer produces approximately 30% more tokens for the same text, and the Claude Opus 4.7 announcement puts it at roughly 1.0 to 1.35 times for Claude Opus 4.7, varying by content type. Both are Anthropic’s figures for the same text. Our 57% compares each model’s own outputs to identical tasks, so it also counts what each model chose to write. It sets one model against the mean of five, on tasks heavy on code and JSON, and measures characters per token on real outputs. Part of our gap likely reflects what each model chose to write; we haven’t separated that from the tokenizer. Treat 57% as this battery’s measurement, not a constant. Your text will land somewhere else, which is why the calculator takes a sample.
Price your output
Estimated at 6 characters per word (five letters plus a space).
0 characters
Your text stays on your device; the page does not send it anywhere. We count its characters and divide by each model’s measured characters per output token, so this is an estimate, not an exact token count.
At 1,000,000 words a month, output costs from $8.80 on Claude Haiku 4.5 to $136.92 on Claude Fable 5.
- Claude Haiku 4.5$8.803.409 characters per token · 1,760,047 tokens · $5.00 per 1M output tokens
- Claude Sonnet 5$29.312.047 characters per token · 2,931,119 tokens · $10.00 per 1M output tokens
- Claude Opus 4.8$65.392.294 characters per token · 2,615,519 tokens · $25.00 per 1M output tokens
- Claude Opus 5$73.752.034 characters per token · 2,949,853 tokens · $25.00 per 1M output tokens
- Claude Fable 5.1$130.892.292 characters per token · 2,617,801 tokens · $50.00 per 1M output tokens
- Claude Fable 5$136.922.191 characters per token · 2,738,476 tokens · $50.00 per 1M output tokens
Output tokens only; input, caching and retries are not included. List prices from prices.json, each checked against Anthropic’s pricing page on the date shown: Claude Opus 5 2026-10-13, Claude Sonnet 5 2026-10-17, Claude Fable 5 2026-10-13, Claude Opus 4.8 2026-10-13, Claude Fable 5.1 2026-10-17, Claude Haiku 4.5 2026-10-13.
Who writes more for the same task
Models also write different amounts for the same prompt, before the tokenizer matters. In this table 1.00 is the median of the six models on each task. Claude Opus 5’s 1.42 means it wrote 42% more text than the median; its 1.62 means it was billed for 62% more tokens.
| Model | Text written | Tokens billed | One pass cost |
|---|---|---|---|
| Claude Opus 5newer tokenizer | 1.42 | 1.62 | $0.2243 |
| Claude Sonnet 5newer tokenizer | 1.09 | 1.16 | $0.0676 |
| Claude Fable 5newer tokenizer | 0.95 | 1.01 | $0.2556 |
| Claude Opus 4.8newer tokenizer | 0.90 | 0.89 | $0.1146 |
| Claude Fable 5.1newer tokenizer | 0.85 | 0.86 | $0.2904 |
| Claude Haiku 4.5previous tokenizer | 0.79 | 0.59 | $0.0219 |
Text written and tokens billed: each model’s output against the median of the six, 1.00 = median. One pass cost: the average list-price cost of one run through the six tasks (each task ran twice). The six one-pass costs add up to $0.97; the whole Edition 2 battery, all 72 runs, cost $1.95. Data: verbosity-index.json.
Pareto
Pareto is Unbiased’s blended model: several frontier and open models answer every request. If output price is what you are watching, it lists at $3.20 per million output tokens and $0.80 input (pricing), with a 1M-token context window (Pareto 26.10 release notes); the Claude models above list at $5 to $50 per million output tokens. That comparison is per token, not per word: we have not run Pareto through this battery, so we can’t say what it costs per word. Its benchmark results, each with its source, are on the model card.
Method
How these numbers were made
- Battery: 6 task types x 2 runs per model, identical prompts, no length guidance, default settings. 72 runs. Write-up: Verbosity Index Edition 2.
- Characters per output token: total characters each model wrote divided by the output tokens it was billed, over all 12 of its runs. Per-run counts: verbosity-index-e2-raw.json.
- Text written and tokens billed: geometric mean of each model’s per-task ratio to the per-task median.
- Caveats: characters per token reflect the text as well as the tokenizer, and this battery is code and JSON heavy. Word counts use an estimate of 6 characters per word. The Edition 2 execution script is not published; the Edition 1 script is at verbosity-battery.py.
- Who we are: Unbiased runs the Verbosity Index and publishes the raw runs.
Cite or link
Free to cite with a link to this page. Copy this HTML:
<a href="https://unbiased.ai/tools/tokenizer-tax/">The tokenizer tax</a>, Unbiased Verbosity Index Edition 2 (measured August 25, 2026)
Questions
What is a token?
A token is the unit an AI model reads and writes, and the unit it bills by: a chunk of text, often part of a word. On our measurements, 1,000 words of output (about 6,000 characters) come to about 1,760 tokens on Claude Haiku 4.5 at 3.409 characters per token, and about 2,760 tokens at the newer tokenizer’s average of 2.172 characters per token (the mean across five Claude models).
Why do newer Claude models use more tokens per character?
Claude bills per token, and the newer tokenizer fits less text into each token. In our Edition 2 battery, Claude Haiku 4.5 on the previous tokenizer produced 3.409 characters per output token, and the 5 Claude models on the newer tokenizer averaged 2.172, so their outputs used about 57% more tokens per character. That is more than the approximately 30% more tokens for the same text that Anthropic’s pricing page gives for the newer tokenizer. Our figure compares each model’s own outputs on code- and JSON-heavy tasks, so part of the gap is the tokenizer and part is likely what each model wrote; we haven’t separated the two.
How many characters per token do Claude models produce?
In our Edition 2 battery, measured August 25, 2026, characters per output token were: Claude Haiku 4.5 3.409; Claude Opus 4.8 2.294; Claude Fable 5.1 2.292; Claude Fable 5 2.191; Claude Sonnet 5 2.047; Claude Opus 5 2.034. These are averages over six task types and depend on the text as well as the tokenizer.
How much does Claude Opus 5 cost per word of output?
About $0.074 per 1,000 words, or $73.75 per million words. That uses Claude Opus 5's $25 per million output tokens, our measured 2.034 characters per output token, and an estimate of 6 characters per word.
Is there a calculator that converts AI token prices into cost per word?
This page does it for six Claude models. Enter words per month, or paste a sample and say how many times a month you produce text like it. It divides characters by each model's measured characters per output token and multiplies by the list output price.
Does my pasted text leave the browser?
No. The estimate runs in your browser, on your device, and the page does not send your text anywhere. A shared link carries only the character count and copies per month, never the text.
Why isn't Pareto in the table?
We have not run Pareto through this battery, so we have no characters-per-token figure for it and can't price it per word. Its list price is $0.80 input and $3.20 output per million tokens, with a 1M-token context window.