Gemini 3.5 Flash vs GPT-5.5

Google's Gemini 3.5 Flash against OpenAI's GPT-5.5 — price, context and what each is best at. Both are available through one OpenAI-compatible API.

AnyModel — you pay	Gemini 3.5 Flash	GPT-5.5
Vendor	Google	OpenAI
Input / 1M	$0.03	$0.15
Output / 1M	$0.03	$0.15
Context	1M	400K
Best for	Agents	Complex coding

Gemini 3.5 Flash

Google's newest default — frontier smarts at a Flash price.

Gemini 3.5 Flash is Google's freshest GA model: it beats Gemini 3.1 Pro on agentic and coding benchmarks while running about 4× faster, with selectable thinking levels and a 1M-token window — the new default pick of the Gemini line.

More about Gemini 3.5 Flash →

GPT-5.5

OpenAI's flagship for coding, agents and research-grade reasoning.

GPT-5.5 is OpenAI's top general-purpose model and the engine behind modern Codex: state-of-the-art coding, computer use and multi-step reasoning with a 400K-token window on this route. The default pick when you want one model that handles everything.

More about GPT-5.5 →

Quick take: pick Gemini 3.5 Flash when cost matters most; pick Gemini 3.5 Flash when you need the largest context. With AnyModel you don't have to choose up front — switch the model id any time.

FAQ

Which is cheaper, Gemini 3.5 Flash or GPT-5.5?

Gemini 3.5 Flash is cheaper on output tokens ($0.03 vs $0.15 per 1M).

Which has a larger context window, Gemini 3.5 Flash or GPT-5.5?

Gemini 3.5 Flash has the larger context window (1M).