OpenAI: GPT-5.6 Luna Pro vs Google: Gemini 3.1 Flash Lite
Side-by-side comparison of specs, pricing, benchmark scores, and task rankings. Updated 2026-11-07.
| OpenAI: GPT-5.6 Luna Pro | Google: Gemini 3.1 Flash Lite | |
|---|---|---|
| Vendor | openai | |
| Quality Score | 100 | 100 |
| Input Price | $0.20/M | $0.25/M |
| Output Price | $1.20/M | $1.50/M |
| Context Window | 1,050,000 | 1,048,576 |
| Max Output | 128,000 | 65,536 |
| Tool Calling | ✓ | ✓ |
| Structured Output | ✓ | ✓ |
| Reasoning Mode | ✓ | ✓ |
| Vision | ✓ | ✓ |
| Audio | - | ✓ |
The verdict
For a sample job of 1 million input tokens and 250,000 output tokens, GPT-5.6 Luna Pro costs $0.50 and Gemini 3.1 Flash Lite costs $0.62, so GPT-5.6 Luna Pro is about 1.2 times cheaper for the same work.
Both take in a similar amount of text: 1,050,000 and 1,048,576 tokens, about 1,575 and 1,573 pages.
Only Gemini 3.1 Flash Lite offers audio input and video input.
Across the 5 tasks where they differ, GPT-5.6 Luna Pro scores higher on 5 (SQL Generation, CSV / Spreadsheet Cleanup, Bulk Data Labeling and others).
GPT-5.6 Luna Pro was released in July 2026 and Gemini 3.1 Flash Lite in May 2026.
Pick GPT-5.6 Luna Pro if you need lower cost or the stronger all-round task scores; pick Gemini 3.1 Flash Lite if you need audio input or video input.
Costs use current list prices per million tokens; page counts assume about 0.75 words per token and 500 words per page.
Who wins by task?
| Task | OpenAI: GPT-5.6 Luna Pro | Google: Gemini 3.1 Flash Lite |
|---|---|---|
| SQL Generation | 133 | 133 |
| CSV / Spreadsheet Cleanup | 133 | 133 |
| Bulk Data Labeling | 129 | 129 |
| Long-Document Summarization | 137 | 137 |
| Blog Post Writing | 121 | 121 |
Scores reflect capability match + benchmark data + pricing for each task. Methodology →