OpenAI: GPT-6 Luna Pro (batch) vs Google: Gemini 3.8 Flash
Side-by-side comparison of specs, pricing, benchmark scores, and task rankings. Updated 2026-09-27.
| OpenAI: GPT-6 Luna Pro (batch) | Google: Gemini 3.8 Flash | |
|---|---|---|
| Vendor | openai | |
| Quality Score | 100 | 100 |
| Benchmark Score | - | 69.0 |
| Input Price | $0.05/M | $0.75/M |
| Output Price | $0.25/M | $3.75/M |
| Context Window | 1,050,000 | 1,048,576 |
| Max Output | 128,000 | 65,536 |
| Tool Calling | ✓ | ✓ |
| Structured Output | ✓ | ✓ |
| Reasoning Mode | ✓ | ✓ |
| Vision | ✓ | ✓ |
| Audio | - | ✓ |
| Benchmark Scores | ||
| ai_index | - | 67.5 |
The verdict
For a sample job of 1 million input tokens and 250,000 output tokens, GPT-6 Luna Pro (batch) costs $0.11 and Gemini 3.8 Flash costs $1.69, so GPT-6 Luna Pro (batch) is about 15.0 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 3.8 Flash offers audio input and video input.
Across the 20 tasks where they differ, GPT-6 Luna Pro (batch) scores higher on 2 (JSON Extraction, Bulk Data Labeling), Gemini 3.8 Flash on 18 (SQL Generation, Code Review, Code Completion and others).
Pick GPT-6 Luna Pro (batch) if you need lower cost; pick Gemini 3.8 Flash if you need audio input, video input or the stronger all-round task scores.
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-6 Luna Pro (batch) | Google: Gemini 3.8 Flash |
|---|---|---|
| SQL Generation | 134 | 141 |
| Code Review | 132 | 144 |
| Code Completion | 131 | 132 |
| Code Refactoring | 136 | 146 |
| Bug Fixing | 136 | 148 |
| Unit Test Generation | 124 | 132 |
| Code Documentation | 131 | 137 |
| Regex Writing | 119 | 125 |
| CI/CD Pipelines | 120 | 128 |
| Frontend Component Design | 122 | 130 |
| Data Analysis | 124 | 134 |
| CSV / Spreadsheet Cleanup | 134 | 136 |
| ETL Scripting | 128 | 137 |
| JSON Extraction | 131 | 131 |
| Bulk Data Labeling | 129 | 128 |
| OCR / Document Parsing | 131 | 134 |
| Table Extraction from PDFs | 131 | 134 |
| Long-Document Summarization | 138 | 148 |
| Short-Form Summarization | 123 | 126 |
| Blog Post Writing | 122 | 129 |
Scores reflect capability match + benchmark data + pricing for each task. Methodology →