Why the same paragraph costs three times more in Japanese
Language models do not read characters or words. They read tokens: fragments produced by a byte-pair encoding that was trained by merging the most frequent sequences in a corpus. Common English words end up as one token each. Everything else gets chopped into pieces — and you pay per piece, in both directions.
The rule of thumb, and where it breaks
The figure everyone quotes is one token ≈ 4 characters of English, or about 0.75 words. It holds well for ordinary English prose. It does not hold anywhere else, and the size of the gap is the thing worth knowing before you sign an API budget:
- English prose — about 4 characters per token.
- Cyrillic and Greek — about 2. The alphabet is well covered but the words are not, so they split into two or three pieces each.
- Chinese — about 1.4 characters per token. Common characters and pairs are in the vocabulary; rarer ones are not.
- Japanese — a little over 1. Kana sequences fragment, and mixed kanji-kana morphology gives the tokenizer little to merge.
- Thai and the Indic scripts — around 1, sometimes below it. Written without spaces and with heavy use of combining marks, they are the worst covered of all.
Worked example. Take a 500-character paragraph. In English that is roughly 125 tokens. The same paragraph translated into Japanese runs about 400 characters, and at 1.1 characters per token that is around 360 tokens — nearly three times the cost for the same meaning. Translate your prompt into Japanese and your bill triples; nothing in the pricing page mentions it.
What this costs at scale
At a frontier-model price of $5 per million input tokens, a 1,000-token prompt costs half a cent. Run it 100,000 times a month and it is $500 — and if that prompt is in Japanese, $1,500. The cost of a prompt is a design decision, not a line item:
- Trim the system prompt first. It ships with every single call, unlike the user's message.
- Watch formatting, not just words. JSON with pretty-printed indentation, markdown tables and long unbroken URLs are token-expensive for the information they carry. Repeated whitespace is billed.
- Output is the expensive half. Output tokens usually cost three to four times input tokens. Asking for a shorter answer is often a bigger saving than shortening the question.
Why this page estimates instead of tokenizing
A real tokenizer needs its vocabulary — 100,000 to 200,000 entries, several megabytes. Loading that to count a prompt would make this page heavier than every other tool on the site combined, and it would still be wrong the moment a provider ships a new vocabulary.
So this counter estimates from the writing system: Latin words follow the word-shaped rule that byte-pair encodings actually produce, and scripts without word spaces are counted per character with a published factor. On prose it lands close; on minified code, base64 blobs or dense punctuation it drifts wider, which is why the result is shown as a range and labelled an estimate. If you need the exact number, your provider's tokenizer endpoint is the only source that is exact — and it changes with the model.
FAQ - Frequently Asked Questions
token and token are different entries. Runs of spaces, tabs and blank lines are different — they become tokens of their own. Indented JSON can spend a noticeable share of its tokens on nothing but whitespace.