What specifically differs between Hydrogen and Carbon?

Hydrogen targets speed and efficiency in everyday coding and agent workflows, while Carbon targets deep work on complex tasks. Hydrogen defaults to high and adds xhigh; Carbon defaults to medium. Hydrogen permits 65,536 output tokens without streaming, compared with Carbon’s 32,768. Both have a 65,536-token streaming segment cap.

Why can a long thinking phase produce a short answer?

Thinking and visible text share the output allowance. With high as the default, Hydrogen can spend a small max_tokens budget before finishing the answer. Check usage, stop reason and thinking level together. To manage spend, evaluate a lower thinking level rather than only reducing the answer budget.

Are all documented file and cache features available here?

Native API features are separate from the compatibility contract. Messages does not accept document blocks or URL images; use Base64 images. Google’s announced TTL cache controls and cache-write pricing begin on January 12, 2027. That date does not establish advance availability of those features on RouteMux.

Gemini 4 Hydrogen

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google/gemini-4-hydrogen

For everyday coding and agent workflows, balancing speed and cost.

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Live model playground

Try Gemini 4 Hydrogen here

Tune the request, see the current price ceiling, and inspect the real response without leaving this model page.

streamchat

1Configure input

Prompt

0 / 20,000

Add images

Maximum estimated cost—

2Live result

Your result will appear here

Enter an input on the left. The same RouteMux Playground execution and billing path powers this embedded test.

Context window: 1M
Max output: 1M
Input modalities: TextImage
Output modalities: Text
Capabilities: Vision · Reasoning · Tool calling · JSON mode · Coding
Upstream release: 2026-11-12
RouteMux name: google/gemini-4-hydrogen

What is Gemini 4 Hydrogen

Gemini 4 Hydrogen, released by Google on November 12, 2026, targets everyday coding and enterprise agent workflows. Google emphasizes speed and efficiency, alongside multimodal analysis and tool use. Where Carbon targets deep work on complex tasks, Hydrogen is a candidate for repeated development and agent routines. Compare your own prompts, tool steps and output lengths before concluding that a workload will finish faster or cost less.

Hydrogen defaults to high thinking and offers low, medium, high and xhigh levels. Thinking consumes output tokens, so the length of the visible answer is not the full usage. Input, thinking, function calls and the final answer share a 1,048,576-token window. Hydrogen supports up to 65,536 output tokens in one segment with or without streaming, unlike Carbon's 32,768-token non-streaming cap. Google's million-token output figure still requires continuation between segments; the compatibility APIs do not promise automatic continuation.

RouteMux exposes OpenAI Chat Completions and Anthropic Messages with streaming, ordinary function tools and Base64 images. Office documents, audio, video and hosted tools listed for Google's native APIs do not automatically carry over to these endpoints. Custom temperature, top_p and top_k values are ignored. Cache billing follows actual implicit-cache usage returned by the model; an Anthropic cache_control hint does not establish explicit cache writes.

RouteMux input costs $0.75 per million tokens and output costs $3.75 per million tokens.

Before you choose

What specifically differs between Hydrogen and Carbon?: Hydrogen targets speed and efficiency in everyday coding and agent workflows, while Carbon targets deep work on complex tasks. Hydrogen defaults to high and adds xhigh; Carbon defaults to medium. Hydrogen permits 65,536 output tokens without streaming, compared with Carbon’s 32,768. Both have a 65,536-token streaming segment cap.
Why can a long thinking phase produce a short answer?: Thinking and visible text share the output allowance. With high as the default, Hydrogen can spend a small max_tokens budget before finishing the answer. Check usage, stop reason and thinking level together. To manage spend, evaluate a lower thinking level rather than only reducing the answer budget.
Are all documented file and cache features available here?: Native API features are separate from the compatibility contract. Messages does not accept document blocks or URL images; use Base64 images. Google’s announced TTL cache controls and cache-write pricing begin on January 12, 2027. That date does not establish advance availability of those features on RouteMux.

Gemini 4 Hydrogen API pricing

Prices verified 2026-11-14

InputOfficial $1.5 / M tokens

$0.75/ M tokensSave 50%

OutputOfficial $7.5 / M tokens

$3.75/ M tokensSave 50%

Cache read $0.0375/M · Cache write —/M

Estimate cost

Input tokensOutput tokens

Estimated cost$0.01125

Key capabilities

Everyday coding and agents: Google positions Hydrogen around speed and efficiency for everyday coding, enterprise agents, multimodal analysis and tool use.
High by default, plus xhigh: The model offers low, medium, high and xhigh. Thinking and the answer share an output budget; consult the published parameter matrix for values accepted by each compatibility endpoint.
65,536 tokens in either mode: Both streaming and non-streaming requests have a 65,536-token segment cap. Million-token output requires continuation across segments.
Images alongside tool history: Compatibility endpoints accept Base64 images and ordinary function tools, including images inside tool results. Check endpoint support separately for office files and Google-hosted tools.

Common use cases

Everyday development: A use named by Google: integrate code analysis, changes and checks into repeated development tasks.
Enterprise agent workflows: Another stated use: progress through business tasks with several tool calls and continue from the returned results.
Multimodal analysis: Google includes multimodal analysis in Hydrogen’s positioning. Base64 image understanding and images returned by tools are supported starting points on these compatibility endpoints.

Limited time10% extra Credits on your first top-up — up to 200 bonus Credits

Applies to your first top-up within 72 hours of signing up. Minimum $20, once per account.

Interface and protocols

OpenAI Chat CompletionsStreamingAnthropic MessagesStreaming

Use any of these IDs to call this model via the API.

RouteMux namegoogle/gemini-4-hydrogen

Replace the ROUTEMUX_KEY placeholder with your API key. Create one →

from openai import OpenAI

client = OpenAI(
    base_url="https://api.routemux.com/v1",
    api_key="<ROUTEMUX_KEY>",
)

completion = client.chat.completions.create(
    model="google/gemini-4-hydrogen",
    messages=[{"role": "user", "content": "What is the meaning of life?"}],
)
print(completion.choices[0].message.content)

base_url: https://api.routemux.com/v1

Performance (last 30 days)

5 requests · last 30 days

Total usage2.3K

P50 first-token latencyInsufficient data (5 requests)

Avg throughputInsufficient data (5 requests)

Success rate39.1%

Uptime · 24htested via openai_chat

39.13%

Success rate · 60d · from real requests

Gemini 4 Hydrogen FAQ

›What is Gemini 4 Hydrogen?

For everyday coding and agent workflows, balancing speed and cost.

›How large is the context window of Gemini 4 Hydrogen?

Gemini 4 Hydrogen supports a context window of up to 1M tokens, with up to 1M output tokens per request.

›How much does the Gemini 4 Hydrogen API cost?

Through RouteMux, Gemini 4 Hydrogen costs $0.75 for input and $3.75 for output (USD per 1M tokens), below the official list price.

›How do I call Gemini 4 Hydrogen via API?

Gemini 4 Hydrogen is OpenAI-compatible: point your base URL at RouteMux and set the model field to google/gemini-4-hydrogen — no code changes needed.

›Which input and output modalities does Gemini 4 Hydrogen support?

Gemini 4 Hydrogen accepts text, image as input and produces text as output.

›When was Gemini 4 Hydrogen released?

Gemini 4 Hydrogen was released on November 12, 2026.

Sources

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