Gemini 4 Carbon opens to everyone at $2/$10, doubling to $4/$20 on December 1st

What happened

Gemini 4 Carbon, announced two weeks ago for "a subset of cyber defenders", is now available to everyone. Simon Willison also shipped llm-gemini 0.36 with support for it.

Key details

• Launch pricing is $2/million input and $10/million output — the same as GPT-6.1 Sol / Claude Sonnet 5.5.
• That pricing is temporary: it doubles to $4/$20 on December 1st, matching Opus 5.5. The author calls it "Google's best ever Gemini".
• The model supports low/medium/high thinking efforts and defaults to medium. The author tested all three with pelican prompts.
• He also tested it in Google's Antigravity IDE with a prompt first tried on Claude Fable 5.2: a Three.js animation where a mech stands up and stomps around Manhattan, Queens and Brooklyn using OpenStreetMap data. The result required an extra prompt — "build that into a standalone HTML file" — to produce a version with no external dependencies, which he screen-captured as a video.
• Update: he spotted on YouTube (tweeted by Sundar Pichai) that with Antigravity's /swarm feature, Carbon built an open-world 3D game — a pelican riding a GBike around Google's Mountain View campus — coordinating subagents to model 3D assets in Blender from Omni and Nano Banana references, build the browser game in Three.js with WebGL shaders, and pair procedural Web Audio sound effects with Lyria music. A playable version is live in AI Studio.

Why it matters

• The pricing strategy is notable: launching at GPT-6.1 Sol / Claude Sonnet 5.5 levels and doubling to Opus 5.5 levels within two weeks means the current price is a promotional one; teams with procurement plans should treat December 1st as a cost milestone.
• The Antigravity /swarm demo shows a full multi-subagent workflow — end-to-end output spanning 3D modeling, shader programming, audio and music generation — a public example of such agent capabilities in real engineering.
• Generating a standalone HTML file still needed an extra prompt, indicating zero-dependency deliverables are not yet default behavior.

Who it affects

• Developers planning API access to the model: the current price window closes December 1st.
• Users of the llm-gemini plugin in Willison's toolchain: version 0.36 adds support.
• Engineering teams watching multi-agent orchestration: the /swarm case offers a practical reference.

Gemini 4 Carbon was announced two weeks ago for "a subset of cyber defenders", but today it's available to everyone else.

This is Google's best ever Gemini, priced at $2/million input and $10/million output at launch (that's GPT-6.1 Sol / Claude Sonnet 5.5 prices) but scheduled to double in price to $4/$20 on December 1st (same as Opus 5.5).

Here are three pelicans for the low, medium and high thinking efforts (it defaults to medium). This is the pelican I got for high:

Gemini pelicans have all been great for a while now, so I also tested it out using Google's Antigravity IDE with a prompt I first tried with Claude Fable 5.2 yesterday:

Make a three js animation where yonkers stands up as a big mech (cool stand up motion) and stomps around manhattan and queens and Brooklyn, use openstreetmap mapping data

Here's the HTML result (I had to prompt "build that into a standalone HTML file" to get a version with no external dependencies). I then screen-captured that as a video:

Update: Huh, just saw this on YouTube (and tweeted by Sundar Pichai):

Using Google Antigravity’s /swarm feature, Carbon built an open-world 3D game where you explore Google’s Mountain View campus as a pelican riding a GBike — coordinating subagents to model 3D assets in Blender from Omni and Nano Banana references, build the browser game in Three.js with WebGL shaders, and pair procedural Web Audio sound effects with Lyria music.

Here's the playable version in AI Studio.

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