Gemini 3.5 Flash vs GPT-5.6 Luna
Gemini 3.5 Flash and GPT-5.6 Luna are both current production-tier models. GPT-5.6 Luna is meaningfully cheaper at $1 / $6 per 1M. Gemini 3.5 Flash leads on coding, reasoning, long-context retrieval.
Specs side by side
| Metric | Google Gemini 3.5 Flash | OpenAI GPT-5.6 Luna |
|---|---|---|
| Input price (per 1M) | $1.5 | $1 |
| Output price (per 1M) | $9 | $6 |
| Context window | 1.0M tokens | 1.1M tokens |
| Speed tier | fast | fast |
| Open weights | No | No |
| EU region | Yes | Yes |
| Free tier | Google AI Studio | No |
| Prompt caching | Yes | Yes |
| Vision input | Yes | Yes |
| Extended thinking | Yes | Yes |
When to choose each
Choose Gemini 3.5 Flash if…
- You want a free tier for prototyping
- Coding is central to your workload
- Reasoning is central to your workload
Choose GPT-5.6 Luna if…
- GPT-5.6 Luna is in the same tier as Gemini 3.5 Flash — pick by provider preference or API ecosystem
Benchmark delta
Gemini 3.5 Flash leads on
- Coding
- Reasoning
- Long-context retrieval
- Multilingual
- Vision
GPT-5.6 Luna leads on
GPT-5.6 Luna has no meaningful benchmark lead in this pair.
FAQ — Gemini 3.5 Flash vs GPT-5.6 Luna
Gemini 3.5 Flash vs GPT-5.6 Luna — which is better?
Gemini 3.5 Flash and GPT-5.6 Luna are both current production-tier models. GPT-5.6 Luna is meaningfully cheaper at $1 / $6 per 1M. Gemini 3.5 Flash leads on coding, reasoning, long-context retrieval. The right pick depends on your use case — see "When to choose each" above for a data-driven decision.
How does Gemini 3.5 Flash pricing compare to GPT-5.6 Luna?
Gemini 3.5 Flash costs $1.5 / $9 per 1M vs GPT-5.6 Luna at $1 / $6 per 1M. GPT-5.6 Luna is cheaper on output tokens by roughly 50%. Both support prompt caching, which reduces effective cost by 80-90% on repeat system prompts.
Does Gemini 3.5 Flash or GPT-5.6 Luna have the bigger context window?
GPT-5.6 Luna has a 1.1M-token context window — 1× the 1.0M context of Gemini 3.5 Flash. Enough for entire codebases, books, or multi-document RAG.
Is there a free tier for Gemini 3.5 Flash or GPT-5.6 Luna?
Gemini 3.5 Flash: yes — Reduced daily quota via AI Studio for prototyping. GPT-5.6 Luna: no — Low-cost at $1/$6 per 1M; starter credits only.
Which is better for coding — Gemini 3.5 Flash or GPT-5.6 Luna?
Gemini 3.5 Flash leads on coding benchmarks (Gemini 3.5 Flash: 91/100, GPT-5.6 Luna: 85/100). For production coding agents also weigh tool-use performance — Gemini 3.5 Flash scores 90, GPT-5.6 Luna scores 87.