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Gemini 4 Hydrogen vs Gemini 4 Argon: which to use for coding

AutoRouter9 min read

Key facts

As of November 12, 2026, move everyday coding to Gemini 4 Hydrogen: feature work, code edits, test runs, codebase questions and the worker agents a larger task fans out to. Keep Gemini 4 Argon, or Gemini 4 Carbon, for long, hard reasoning. That split is Google's own advice, published the day Hydrogen came out. Hydrogen costs $1.50 per million input tokens and $7.50 per million output tokens. Argon costs $2 and $10 through November 30, 2026, then $4 and $20. AutoRouter, the Mac app for Codex and Claude Code, wrote this post, has Gemini 4 Hydrogen in its model picker and worked the prices through: one assumed agent request costs $0.0259 on Hydrogen, $0.0345 on Argon now and $0.069 on Argon from December 1.

Every outside figure below comes from Google's own pages, linked where it is used and checked on November 12, 2026.

What is Gemini 4 Hydrogen?

Gemini 4 Hydrogen is Google's fast, efficient Gemini 4 model for everyday coding and agentic work. Google announced it on November 12, 2026 as the upgrade for teams on Gemini 3.8 Flash, and describes Carbon and Argon as its models for deep, long-horizon reasoning. As of November 12, 2026, Google's model page and What's new in Gemini 4 Hydrogen give these details:

Which coding work belongs on Hydrogen, and which stays on Argon?

Day-to-day coding and the steps inside a larger task go to Gemini 4 Hydrogen, and the hardest reasoning stays on Argon or Carbon. Google's developer docs split the work this way as of November 12, 2026:

Kind of workGoogle points toWhy (Google, November 12, 2026)
Everyday coding and interactive web appsHydrogenThe docs list both as Hydrogen's work.
Tool-using agents and parallel subagentsHydrogenThe docs list both, and Antigravity's agent now uses Hydrogen as its default.
Code edits, subagent tasks and test runs inside a planned changeHydrogenIn the split the docs describe, Carbon plans and Hydrogen carries out the steps.
Advanced long-horizon tasksArgonThe docs say Argon suits most of these and uses fewer tokens than Carbon.
Hard architecture, debugging and security auditsCarbonThe docs say Carbon is the strongest model and spends more thinking tokens on these.
Moving off Gemini 3.8 FlashHydrogenThe docs name it the recommended upgrade.

Google also says to try all four thinking levels and keep the lowest one that meets your quality bar. Moving from Argon to Hydrogen needs no change to the request beyond the model ID. Which model to use for which coding task maps the rest of your work to a model tier, and Gemini 4 Carbon vs Gemini 4 Argon covers the top of the Gemini 4 family.

What does Gemini 4 Hydrogen cost next to Argon and Carbon?

Gemini 4 Hydrogen costs $1.50 per million input tokens and $7.50 per million output tokens, three quarters of Argon's price through November 30, 2026 and three eighths of it from December 1 (Google's pricing page, as of November 12, 2026). Google's pricing page lists no scheduled price change for Hydrogen.

List price per million tokens, November 12, 2026Gemini 4 HydrogenGemini 4 Argon and Gemini 4 CarbonClaude Opus 5.5
MakerGoogleGoogleAnthropic
Input$1.50$2 through November 30, then $4$4
Cached input$0.075$0.10 through November 30, then $0.20$0.20
Cache writeNone listed; caching is automaticNone listed$5 (5-minute), $8 (1-hour)
Output, thinking included$7.50$10 through November 30, then $20$20
Batch and Flex$0.75 input, $3.75 outputArgon: $1 input, $5 output through November 30Not compared here

The arithmetic below prices the assumed agent request this blog's pricing posts use: 45,000 cached input tokens, 5,000 new input tokens and 2,000 output tokens, thinking included. Google lists no cache-write price for Hydrogen, so new input bills at the input price. Caching is implicit, and the example assumes all 45,000 repeated tokens hit the cache, which Google's caching guide does not promise.

Assumed request: 45,000 cached input, 5,000 new input, 2,000 output tokens
Google's Standard list prices per million tokens as of November 12, 2026

Gemini 4 Hydrogen
  45,000 cached input  x  $0.075  =  $0.003375
   5,000 new input     x  $1.50   =  $0.0075  (no cache-write price listed)
   2,000 output        x  $7.50   =  $0.015
  Total                              $0.025875, about $0.0259

Gemini 4 Argon, through November 30, 2026      $0.0345
Gemini 4 Argon, from December 1, 2026          $0.0690

Each extra 1,000 thinking or output tokens
  Hydrogen: + $0.0075     Argon: + $0.01, then + $0.02

At these prices, $20 of API usage pays for 772 of these requests on Hydrogen, against 579 on Argon now and 289 from December 1. The same request costs $0.074 on Claude Opus 5.5, as worked in Claude Fable 5.2 vs Opus 5.5: which to use for coding. The arithmetic gives every model the same token counts, and real counts differ. Hydrogen thinks at high unless you set a lower level, while Argon starts at medium, so a request left at each model's default can spend more thinking tokens on Hydrogen.

What does Google claim about Gemini 4 Hydrogen, and who measured it?

Google claims Gemini 4 Hydrogen edges past Argon on a broad intelligence index and runs much faster than the model it replaces. Every figure below is Google's, from its November 12, 2026 announcement, with the thinking level where Google names one.

Claim, as Google states it on November 12, 2026Thinking level Google namesWho ran it
Artificial Analysis Intelligence Index: 51 for Hydrogen against 50 for Argonhigh, Hydrogen's defaultArtificial Analysis, reported by Google
Artificial Analysis Intelligence Index: 54 for HydrogenxhighArtificial Analysis, reported by Google
Terminal-Bench 4.1: 57% for Hydrogen against 18.2% for Gemini 3.8 FlashNot namedGoogle
Finishes tasks 2.5 times faster than Gemini 3.8 Flashhigh, Hydrogen's defaultGoogle
On Terminal-Bench 4.0 in Antigravity, with Carbon coordinating and Hydrogen running worker and verifier agents: task success near Carbon's, with 24% less quota on average and 19% fasterNot namedGoogle

To judge your own work, run one everyday task and one hard task from your backlog on Hydrogen and on the model you use now, and compare the results and the token counts.

How do you try Gemini 4 Hydrogen in Codex or Claude Code?

Use a gateway that lists the model, such as OpenRouter, or pick Gemini 4 Hydrogen in the model picker if you use AutoRouter. As of November 12, 2026, Google's docs have no guide for running Hydrogen inside either app.

AutoRouter has not run Hydrogen through OpenRouter for this post, so follow OpenRouter's guides for the exact settings. Try a new model in Codex or Claude Code without another API key covers both routes.

How does AutoRouter handle Gemini 4 Hydrogen?

Gemini 4 Hydrogen is in AutoRouter's model picker, where you can choose it yourself or name it in a plain-English rule. AutoRouter, the Mac app for Codex and Claude Code, puts new models in the picker you already use right away, with no keys or endpoints to set up.

Models outside your ChatGPT and Claude plans come with AutoRouter Pro, at $50 a month with $20 of included usage each month. Paid models bill at the provider's price plus 10%, which AutoRouter earns. The AutoRouter team tests every new model as it becomes available. AutoRouter runs on macOS 14 or later and is in beta, and requests pass through its servers on their way to each provider (AutoRouter privacy).

Questions

Is Gemini 4 Hydrogen better than Gemini 4 Argon at coding?

For everyday coding, Google points to Hydrogen, and for advanced long-horizon tasks it points to Argon. Google reports Hydrogen at 51 on the Artificial Analysis Intelligence Index at high against Argon's 50, as of November 12, 2026. That index is broad, and the announcement's text gives no coding benchmark with the two side by side, so test both on a task from your own backlog.

Can Gemini 4 Hydrogen replace Gemini 4 Carbon or Claude Opus 5.5 on hard work?

Google does not say so. Its docs keep hard architecture, debugging and security audits on Carbon, and its Antigravity result pairs Hydrogen with Carbon as the coordinator. The announcement's text compares Hydrogen with no Claude model. Keep hard work on the strongest model you trust for it, and give Hydrogen the steps around it.

Which thinking level should you use with Gemini 4 Hydrogen?

Start at high, the default, and test lower levels against your quality bar. Google's docs suggest medium for interactive coding, low for cost- or latency-sensitive work, and xhigh only for hard multi-step problems, since it adds latency and tokens and can overthink simple prompts.

Does Gemini 4 Hydrogen replace Gemini 3.8 Flash?

Yes, Google names Hydrogen the recommended upgrade from Gemini 3.8 Flash and earlier Gemini 3 and 2.5 models. Its migration checklist says to change the model ID, raise low max_output_tokens caps, test medium and high because the default is now high, and drop explicit caching, temperature, top_p and top_k.

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