Gemini 4 Carbon and Argon cost $2/$10 per million tokens until Nov 30, then double. Hydrogen is $1.50/$7.50, about 15x the input price of Haiku 5.5 and GPT-6 Luna, which affects model choice.
Key takeaways · AI-distilled
Gemini 4 Carbon and Argon cost the same per tokenThe chunk of text a model reads and writes in — roughly three-quarters of a word — and the unit AI usage is billed in.Full definition →, but Google says Argon spends fewer tokens per turn, so Simon Willison notes Argon should cost less per task at the identical price.
Hydrogen is only 25% cheaper than Carbon and Argon today. After their prices double on December 1 it becomes a 75% discount, which is when Simon Willison says its pricing starts to make sense.
Willison's pelican-drawing comparison across all three models and three effort levels showed a stark quality drop for Hydrogen relative to how close its price is to its siblings.
Google positions Hydrogen as a fast execution model for writing code and running tests alongside Carbon or Argon. It is also the new free-tier model and will power AI features in Google Search.
Terms in this piece · Glossary
token — The chunk of text a model reads and writes in — roughly three-quarters of a word — and the unit AI usage is billed in.
