High-volume, cost-sensitive work
Choose GPT-5.6 Luna
GPT-5.6 Luna costs 20% less on a typical mix of three input tokens for every output token ($0.45 against $0.56 per million tokens).
Gemini 3.1 Flash-Lite vs GPT-5.6 Luna: price, context and capabilities
Choose GPT-5.6 Luna for high-volume, cost-sensitive work, writing and code generation, reused prompts and documents (RAG, agents) and the latest release; on the other points the two are level or the data is missing.
In short
- GPT-5.6 Luna is 20% cheaper than Gemini 3.1 Flash-Lite at the headline price ($0.45 / 1M tokens vs $0.5625 / 1M tokens).
- GPT-5.6 Luna reads more per request: 1.05M tokens against 1.05M.
- GPT-5.6 Luna is the newer model (Jul 9, 2026, against May 2026).
Which should you choose?
Each answer below comes straight from the published prices, specifications and independent benchmark results.
Writing and code generation
Choose GPT-5.6 Luna
GPT-5.6 Luna charges $1.20 per million output tokens, against $1.50 for Gemini 3.1 Flash-Lite. Output dominates the bill when answers are long.
Reused prompts and documents (RAG, agents)
Choose GPT-5.6 Luna
GPT-5.6 Luna charges $0.02 per million cached input tokens, against $0.03 for Gemini 3.1 Flash-Lite.
Latest release
Choose GPT-5.6 Luna
GPT-5.6 Luna is the newer release (Jul 9, 2026, against May 2026 for Gemini 3.1 Flash-Lite).
Monthly cost at three volumes
| Volume | Gemini 3.1 Flash-Lite | GPT-5.6 Luna | Difference |
|---|---|---|---|
| Prototype: 1M input, 250K output tokens | $0.63 | $0.50 | GPT-5.6 Luna, $0.13 less |
| Production: 20M input, 5M output tokens | $12.50 | $10.00 | GPT-5.6 Luna, $2.50 less |
| Scale: 500M input, 100M output tokens | $275.00 | $220.00 | GPT-5.6 Luna, $55.00 less |
Standard rates, without caching or batch discounts. Volumes are per month.
Specifications side by side
| Gemini 3.1 Flash-Lite | GPT-5.6 Luna | |
|---|---|---|
| Provider | OpenAI | |
| Category | Language models | Language models |
| Status | Legacy | Generally available |
| Headline price | $0.5625 / 1M tokens | $0.45 / 1M tokens |
| Input | $0.25 / 1M tokens | $0.20 / 1M tokens |
| Output | $1.50 / 1M tokens | $1.20 / 1M tokens |
| Cached input | $0.025 / 1M tokens | $0.02 / 1M tokens |
| Context window | 1.05M | 1.05M |
| Max output | 66k | 128k |
| Released | May 2026 | Jul 9, 2026 |
| Knowledge cutoff | No data | February 2026 |
| Licence | Proprietary | Proprietary |
| Capabilities | Vision, Reasoning, Tool calling, Structured output, Prompt caching, Batch API | Vision, Reasoning, Tool calling, Structured output, Prompt caching, Batch API |
| API model id | gemini-3.1-flash-lite | gpt-5.6-luna |
Benchmarks side by side
Leader in bold.
| Benchmark | Gemini 3.1 Flash-Lite | GPT-5.6 Luna |
|---|---|---|
| Intelligence Index | No data | 37.3 |
| SciCode | No data | 53.6% |
| GPQA Diamond | No data | 91.1% |
| Humanity's Last Exam | No data | 39.5% |
| MMMU-Pro (visual reasoning) | No data | 78.6% |
| Long-context reasoning (AA-LCR) | No data | 83.7% |
Independent evaluations by Artificial Analysis, run the same way for every model, at the reasoning setting shown. Percentages unless marked as an index.
Frequently asked questions
Should I choose Gemini 3.1 Flash-Lite or GPT-5.6 Luna?
Choose GPT-5.6 Luna for high-volume, cost-sensitive work, writing and code generation, reused prompts and documents (RAG, agents) and the latest release; on the other points the two are level or the data is missing.
Which is cheaper, Gemini 3.1 Flash-Lite or GPT-5.6 Luna?
GPT-5.6 Luna is 20% cheaper than Gemini 3.1 Flash-Lite at the headline price ($0.45 / 1M tokens vs $0.5625 / 1M tokens).
Which has the larger context window, Gemini 3.1 Flash-Lite or GPT-5.6 Luna?
GPT-5.6 Luna reads more per request: 1.05M tokens against 1.05M.
What is the difference between Gemini 3.1 Flash-Lite and GPT-5.6 Luna?
Gemini 3.1 Flash-Lite is made by Google and GPT-5.6 Luna by OpenAI. GPT-5.6 Luna is 20% cheaper than Gemini 3.1 Flash-Lite at the headline price ($0.45 / 1M tokens vs $0.5625 / 1M tokens). GPT-5.6 Luna reads more per request: 1.05M tokens against 1.05M. GPT-5.6 Luna is the newer model (Jul 9, 2026, against May 2026).
How much do Gemini 3.1 Flash-Lite and GPT-5.6 Luna cost per month?
At 20 million input and 5 million output tokens a month, Gemini 3.1 Flash-Lite costs $12.50 and GPT-5.6 Luna costs $10.00, at standard rates.
Which is newer, Gemini 3.1 Flash-Lite or GPT-5.6 Luna?
GPT-5.6 Luna was released on Jul 9, 2026 and Gemini 3.1 Flash-Lite on May 2026.