Guide
The new tokenizer that adds ~30% more tokens
Same rate card, higher bill: the newer models count tokens differently.
What changed
Claude Opus 4.7 and later, Fable 5, and Sonnet 5 use a newer tokenizer that produces about 30% more tokens for the same characters. Sonnet 4.6 and earlier use the old tokenizer. Because you are billed per token, the same prompt can cost ~30% more even though the per-token price is unchanged.
Why estimates undercount
Any cost estimate based on character or word counts with the old tokenizer will undercount these models. JP the Cat prices from the real token counts in your logs, so the inflation is already in the number.
Common questions
- Does the new tokenizer change the per-token price?
- No — the rate is the same. It changes how many tokens the same text becomes, which is what you pay for.
See your real numbers with JP the Cat
A light, local menu-bar meter for Claude Code, Codex, Grok, and Muse Spark — real cost, honest limits.
Download MeowPrefer Homebrew? Install the same signed, notarized app from JP's public tap.
brew tap 8bittts/jpthecat
brew trust 8bittts/jpthecat
brew install --cask jpthecat