Gemini 4 Hydrogen vs Claude Sonnet 5.5: 7 of 10 Benchmarks

Head-to-Head: Gemini 4 Hydrogen and Claude Sonnet 5.5 on Google's 10-Benchmark Model Card

Gemini 4 Hydrogen beats Claude Sonnet 5.5 on 7 of the 10 benchmarks in Google's own model card and costs about a third as much to run the Artificial Analysis Intelligence Index. Claude Sonnet 5.5 still leads on terminal coding (63.9% vs 57.0% on Terminal-Bench 4.1), computer use and scientific terminal tasks. Hydrogen is the better pick for cheap, fast agentic execution at volume, and Sonnet 5.5 is the better pick for terminal-heavy and computer-use workloads. Google released Hydrogen on November 12, 2026, so most numbers here are vendor-reported, and independent head-to-head testing is still thin.

Key Takeaways

• Google's own card shows a 7-to-3 split. On the 10-row table in the official model card, Hydrogen leads Sonnet 5.5 on SWE-sweep, Agents' Last Exam, AutomationBench-AA, Vending-Bench 2, MKA, Chartography and one other row. Sonnet 5.5 leads on Terminal-Bench 4.1, OSWorld-2.1 and Terminal-Bench-Science 0.1.
• Sonnet 5.5 is 1 point higher on the independent Artificial Analysis index. Artificial Analysis scores Hydrogen 54 at its xhigh setting and Sonnet 5.5 55 at max.
• Cost is Hydrogen's clearest advantage. Artificial Analysis estimates Hydrogen costs about 32% of what Sonnet 5.5 does per index run.
• The speed advantage is reported but not officially measured head-to-head. Google says Hydrogen is 2.5x faster than Gemini 3.8 Flash. The only direct comparison with Sonnet 5.5 is a community claim of 2.4x.
• Several Sonnet 5.5 details are missing. The sources reviewed for this page do not include Sonnet 5.5's context window or full official pricing.

Gemini 4 Hydrogen vs Claude Sonnet 5.5 at a Glance

Dimension	Gemini 4 Hydrogen	Claude Sonnet 5.5
Positioning	Google's fast "everyday coding and agentic workflows" model, adapted from Gemini 4 Carbon (official)	Anthropic's mid-tier model; Google uses it as the comparison point in the Hydrogen launch
Wins on Google's 10-row model card	7 of 10	3 of 10 (Terminal-Bench 4.1, OSWorld-2.1, Terminal-Bench-Science)
AA Intelligence Index (top setting)	54 (xhigh)	55 (max), per Artificial Analysis
API list price per 1M tokens	$1.50 input / $7.50 output (official)	$2 input (single community source, unconfirmed); output not yet confirmed
Relative cost per AA index run	About 32% of Sonnet 5.5's	Baseline
Context window	1,048,576 tokens, unified input and output (official)	Not yet confirmed
Thinking levels	LOW, MEDIUM, HIGH (default), XHIGH	Not yet confirmed

Gemini 4 Hydrogen is a Flash-class model that scores 54 on the Artificial Analysis Intelligence Index, 1 point behind Claude Sonnet 5.5, at roughly one-third of Sonnet's cost per task.

Benchmarks: Where Each Model Wins

The most complete comparison available is Google's own table in the Gemini 4 Hydrogen model card. It puts Hydrogen next to Claude Sonnet 5.5 and GPT-6.1 Terra. These are vendor-reported numbers. The card does not say which effort setting was used for Sonnet 5.5.

Benchmark (category)	Gemini 4 Hydrogen	Claude Sonnet 5.5	Leader
SWE-sweep (agentic coding)	13.5%	3.1%	Hydrogen
Terminal-Bench 4.1, cheating-adjusted	57.0%	63.9%	Sonnet 5.5
Agents' Last Exam v1.1	71.6%	60.4%	Hydrogen
AutomationBench-AA	76.1%	71.8%	Hydrogen
Vending-Bench 2 (bank balance)	$14,549	$11,165	Hydrogen
OSWorld-2.1, offline subset	77.6%	83.9%	Sonnet 5.5
MKA (Climb WSR accuracy)	53.4%	52.0%	Hydrogen
Chartography	66.6%	61.6%	Hydrogen
Terminal-Bench-Science 0.1	51.4%	59.9%	Sonnet 5.5

The tenth row, a reasoning benchmark, was cut off in the copy of the card available for this page. Community analyst Chris summarized the same chart: Hydrogen leads 7 of 10 rows, and Sonnet 5.5 holds terminal work, computer use and the science subset (post).

Source: @ChrisGPT

The same analyst raises two caveats. The Vending-Bench figure is a simulated final bank balance, not a pass rate. Epoch also reported serious grading weaknesses in the public tasks of Agents' Last Exam v1.1 that it reviewed. Taken together, Hydrogen's largest margins are on benchmarks that deserve the most scrutiny. Sonnet 5.5's leads are on terminal and computer-use benchmarks that are more established.

On the independent AA Intelligence Index, the gap is 1 point. Artificial Analysis scores Hydrogen 54 at xhigh, which puts it one point behind Claude Sonnet 5.5 (max) and GPT-6.1 Sol (max) (Artificial Analysis). At its default high setting, Hydrogen scores 51. Some community posts described the xhigh result as a tie with Sonnet 5.5 (example). The benchmarker's own account gives the 1-point gap.

Source: @HarshithLucky3

On Google's own benchmark table, Claude Sonnet 5.5 beats Gemini 4 Hydrogen by 6.9 points on Terminal-Bench 4.1 and 6.3 points on OSWorld-2.1, its two clearest leads.

Capabilities, Speed and Context Limits

Hydrogen's documented features come from Google's developer guide, the Developer's guide to Gemini 4 Hydrogen:

• Unified context window: 1,048,576 tokens covering input and output combined.
• Long Decode: generation beyond a single 65,536-token segment, up to roughly 1M tokens minus the input.
• Four thinking levels: LOW, MEDIUM, HIGH (the default) and XHIGH.
• Implicit caching: applies automatically to shared prompt prefixes of 4,096 tokens or more. Explicit context caching is not supported.
• Office and OpenDocument inputs: .docx, .pptx, .xlsx and OpenDocument files, alongside PDF.
• Short-term GA lifecycle: Hydrogen is a short-term GA release with a minimum 45-day retirement notice.

Google's launch post also introduces Orchestrator in Google Antigravity. Orchestrator switches between Carbon and Hydrogen within one session. On Terminal-Bench 4.0, Orchestrator came close to Carbon's own success rate while using 24% less quota and finishing 19% faster. Compared with Gemini 3.8 Flash, Hydrogen cuts fabricated claims by more than 5x, according to Google.

On speed, Artificial Analysis measures Hydrogen at 188 output tokens per second. At xhigh it takes 13.7 minutes per index task, and at low it takes 1.3 minutes (Artificial Analysis model page). Arena reported Hydrogen (High) as the fastest model in the Agent Arena top 10, with a typical step time of 7.3 seconds. No official speed number for Sonnet 5.5 appears in the sources reviewed. The "2.4x faster than Sonnet 5.5" figure is a community claim.

The sources reviewed do not confirm Claude Sonnet 5.5's context window, thinking modes or output limits. For background on how Hydrogen fits into Google's lineup, see our explainer on Gemini 4 Hydrogen.

Cost and Access

Gemini 4 Hydrogen is priced at the same rate across its full 1M-token context: $1.50 per million input tokens, $7.50 per million output tokens and $0.075 for cached input. Artificial Analysis puts its cost at $1.87 per index task at high and $3.16 at xhigh. Overall, it estimates Hydrogen's cost at about 32% of Sonnet 5.5's. One community post lists Sonnet 5.5 input at $2 per million tokens (source). That figure is unconfirmed, and no Sonnet output price was found.

Access route	Gemini 4 Hydrogen	Claude Sonnet 5.5
Vendor consumer app	Gemini app, including free use through auto model selection, plus Google Search	Not yet confirmed in the sources reviewed
Vendor API	Gemini API (free and paid tiers), AI Studio, Gemini for business	Not yet confirmed in the sources reviewed
Coding tools	Antigravity (Pro/Ultra), Cursor, Devin, GitHub Copilot	Not yet confirmed in the sources reviewed
kie.ai API	Gemini 4 Hydrogen on kie.ai	Not covered here

Simon Willison pointed out a caveat about Hydrogen's pricing. It is currently only a 25% discount on Carbon and Argon. That gap widens to 75% after December 1, when both larger models double in price (analysis).

Which One Should You Use?

Choose Gemini 4 Hydrogen if:

• You run high-volume agentic pipelines where cost per task matters more than the last point of accuracy.
• Your work is repository bug-fixing, automation or document-heavy multimodal tasks, where the model card shows Hydrogen ahead.
• You want a fast worker model under a Carbon planner through Orchestrator.

Choose Claude Sonnet 5.5 if:

• Your agents work mainly in a terminal. Sonnet 5.5 leads Terminal-Bench 4.1 at 63.9% against 57.0%.
• You depend on computer use. Sonnet 5.5 leads OSWorld-2.1 at 83.9% against 77.6%.
• You need the slightly higher AA index score (55 vs 54) and can absorb roughly 3x the cost per task.

The best-supported conclusion is that Gemini 4 Hydrogen wins on cost-adjusted intelligence, while Claude Sonnet 5.5 keeps its edge on terminal and computer-use benchmarks.

Frequently Asked Questions

Is Gemini 4 Hydrogen better than Claude Sonnet 5.5?

Not across the board. Gemini 4 Hydrogen wins 7 of 10 benchmarks in Google's model card, including SWE-sweep (13.5% vs 3.1%). Claude Sonnet 5.5 leads on Terminal-Bench 4.1, OSWorld-2.1 and Terminal-Bench-Science, and it is 1 point higher on the Artificial Analysis index (55 vs 54).

Is Gemini 4 Hydrogen cheaper than Claude Sonnet 5.5?

Yes. Artificial Analysis estimates that Gemini 4 Hydrogen costs about 32% of what Claude Sonnet 5.5 costs per index run. Hydrogen lists at $1.50 input and $7.50 output per million tokens. Sonnet 5.5's full official pricing was not in the sources reviewed.

Which is better for coding, Gemini 4 Hydrogen or Claude Sonnet 5.5?

It depends on the kind of coding. Claude Sonnet 5.5 is stronger at terminal coding, with 63.9% against 57.0% on Terminal-Bench 4.1. Gemini 4 Hydrogen is stronger at repository bug repair, with 13.5% against 3.1% on SWE-sweep.

Is Gemini 4 Hydrogen faster than Claude Sonnet 5.5?

Probably, but no official head-to-head speed number exists. A community analyst reported that Hydrogen finished the Artificial Analysis evaluation 2.4x faster. Artificial Analysis measures Hydrogen at 188 output tokens per second.

How do Gemini 4 Hydrogen and Claude Sonnet 5.5 compare on the Artificial Analysis Intelligence Index?

Gemini 4 Hydrogen scores 54 at xhigh, 1 point behind Claude Sonnet 5.5 at max. At its default high setting, Hydrogen scores 51.

What context window does Gemini 4 Hydrogen have compared to Claude Sonnet 5.5?

Gemini 4 Hydrogen has a unified 1,048,576-token window covering input and output. The sources reviewed do not confirm Claude Sonnet 5.5's context window.

Can I use Gemini 4 Hydrogen for free?

Yes. Gemini 4 Hydrogen is free in the Gemini app, in Google Search and on the Gemini API free tier, with rate limits. Antigravity access requires Google AI Pro or Ultra.

What to Watch Next

Three things will refine this comparison. The first is independent Terminal-Bench and OSWorld runs that test both models under matched settings. The second is Anthropic's own confirmed Sonnet 5.5 pricing and context limits, which would fill the gaps in the table above. The third is Gemini 4 Krypton, which community testers report seeing on Arena under the Hydrogen name. It could change Google's lineup again; our first look at Gemini 4 Krypton tracks it. This page will be updated as those numbers come in.

Try related models on Kie.ai: Gemini 4 Hydrogen, Claude Sonnet 5.5 and Gemini 4 Argon.