Compare / Models
Gemini 3.8 Flash vs Gemini 4 Hydrogen
Price, context window and capabilities side by side, read from the same catalog that meters your calls, not from a press release.
Gemini 3.8 Flash is 2.0x cheaper on input. Gemini 3.8 Flash is 2.0x cheaper on output. Only Gemini 4 Hydrogen declares vision.
At a glance
Side by side
Google's most capable Flash model, built for long-horizon software engineering and autonomous agents.
Google DeepMind's fast, efficient Gemini 4 model for everyday coding and agentic work: four thinking levels and a 1M-token window at one flat price.
Specifications
Every difference we can measure
| Gemini 3.8 Flash | Gemini 4 Hydrogen | |
|---|---|---|
| Input price | $0.75/M | $1.5/M |
| Output price | $3.75/M | $7.5/M |
| Vision | No | Yes |
| Tool calling | Yes | Yes |
| Prompt caching | Yes | Yes |
| Long context | No | Yes |
A row appears only when we hold the fact for both models. Anything the provider has not published is left out rather than guessed, so an empty row is missing data and never a zero.
Verdict
Which to pick
Gemini 3.8 Flash is $0.75 / $3.75 per million tokens through the end of 2026 and $1.50 / $7.50 after, which is Hydrogen's price, so Hydrogen costs twice as much per token until then and the same after. Google positions it as the upgrade: 2.5 times faster at its default setting, Terminal-Bench 4.1 at 57% against 18.2%, and more than five times fewer fabricated claims. Those are Google's numbers. If your workload is simple and cost-sensitive, keep 3.8 Flash while its introductory price lasts; for agent and coding loops, test Hydrogen.
Keep looking
Related comparisons
FAQ
Frequently asked questions
What is the difference between Gemini 3.8 Flash and Gemini 4 Hydrogen?
Gemini 3.8 Flash is 2.0x cheaper on input. Gemini 3.8 Flash is 2.0x cheaper on output. Only Gemini 4 Hydrogen declares vision. Only Gemini 4 Hydrogen declares long context. Both run on the same endpoint and the same key here, so trying each is a one-line change to the model id.
Which is cheaper, Gemini 3.8 Flash or Gemini 4 Hydrogen?
Gemini 3.8 Flash is, on input tokens. Output usually dominates the bill on generative work, so check the output row above against your own ratio of prompt to completion before deciding.
Can I switch between Gemini 3.8 Flash and Gemini 4 Hydrogen without changing my code?
Yes. Both are OpenAI-compatible through one CompanyFabric key, so switching is the model string and nothing else, no second SDK, no second contract, one prepaid balance across both.
Do I have to choose?
No. Send companyfabric/auto and we route each request to the cheapest model that can serve it, which is how most people use both without deciding in advance.
One key. Every model. Exact prices.
Run Gemini 3.8 Flash and Gemini 4 Hydrogen on the same key and compare them on your own prompts. Free starter credits included, no subscription required.