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, 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), 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.