What does a sentence cost?
AI doesn't read letters or words — it reads Tokens, small chunks of text. Tokens are the currency: they fill the context window (the model's working memory), they show up on the bill, and they are the thinking budget. Here you can watch text break into them.
What you see
A text box with ready-made examples — below it, the text falls apart live into tokens, with a counter and a German/English comparison.
What it shows
AI's currency: tokens fill the context window, appear on the bill and are the thinking budget — and the same statement costs more in German than in English.
12 tokens · 69 characters
- Art
- ificial
- ·intelligence
- ·forget
- s
- ·the
- ·beginning
- ·of
- ·a
- ·long
- ·conversation
- .
· marks a space — it usually belongs to the word that follows. Raw byte values appear when a single character, like an emoji, is split across several tokens.
Same statement, German vs. English:
More letters, far fewer tokens: English is the tokenizer's mother tongue, so the same statement costs three-quarters more in German here.
Shown with the open cl100k_base tokenizer (the vocabulary behind GPT-3.5/GPT-4 — GPT is explained in the glossary), as of July 2026, computed right here in your browser. Claude, GPT & co. each use their own, similarly-working tokenizers — the exact boundaries differ, the principle doesn't.
Why it matters: how a window overflows is in the article on context rot; how model class, thinking depth and iterations set the price is in the three dials; and what happens when you economise on all three is in the ugly cat.