Google: Gemini 3.8 Flash vs OpenAI: GPT-5.6 Terra
Side-by-side comparison of specs, pricing, benchmark scores, and task rankings. Updated 2026-10-19.
| Google: Gemini 3.8 Flash | OpenAI: GPT-5.6 Terra | |
|---|---|---|
| Vendor | openai | |
| Quality Score | 100 | 100 |
| Benchmark Score | 67.8 | 70.0 |
| Input Price | $0.82/M | $2.00/M |
| Output Price | $4.12/M | $12.00/M |
| Context Window | 1,048,576 | 1,050,000 |
| Max Output | 65,536 | 128,000 |
| Tool Calling | ✓ | ✓ |
| Structured Output | ✓ | ✓ |
| Reasoning Mode | ✓ | ✓ |
| Vision | ✓ | ✓ |
| Audio | ✓ | - |
| Benchmark Scores | ||
| ai_index | 67.5 | 69.4 |
The verdict
For a sample job of 1 million input tokens and 250,000 output tokens, Gemini 3.8 Flash costs $1.86 and GPT-5.6 Terra costs $5.00, so Gemini 3.8 Flash is about 2.7 times cheaper for the same work.
Both take in a similar amount of text: 1,048,576 and 1,050,000 tokens, about 1,573 and 1,575 pages.
Only Gemini 3.8 Flash offers audio input and video input.
On our blended benchmark score GPT-5.6 Terra leads 70.0 to 67.8.
Across the 20 tasks where they differ, Gemini 3.8 Flash scores higher on 10 (SQL Generation, Code Completion, Code Documentation and others), GPT-5.6 Terra on 10 (Code Review, Code Refactoring, Bug Fixing and others).
Gemini 3.8 Flash was released in September 2026 and GPT-5.6 Terra in July 2026.
Pick Gemini 3.8 Flash if you need lower cost, audio input or video input; pick GPT-5.6 Terra if you need benchmark performance.
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 | Google: Gemini 3.8 Flash | OpenAI: GPT-5.6 Terra |
|---|---|---|
| SQL Generation | 141 | 140 |
| Code Review | 144 | 145 |
| Code Completion | 132 | 118 |
| Code Refactoring | 146 | 147 |
| Bug Fixing | 148 | 149 |
| Unit Test Generation | 132 | 132 |
| Code Documentation | 137 | 135 |
| Regex Writing | 125 | 124 |
| CI/CD Pipelines | 128 | 128 |
| Frontend Component Design | 130 | 130 |
| Data Analysis | 134 | 134 |
| CSV / Spreadsheet Cleanup | 136 | 135 |
| ETL Scripting | 137 | 137 |
| JSON Extraction | 131 | 121 |
| Bulk Data Labeling | 128 | 117 |
| OCR / Document Parsing | 134 | 134 |
| Table Extraction from PDFs | 134 | 134 |
| Long-Document Summarization | 148 | 147 |
| Short-Form Summarization | 126 | 116 |
| Blog Post Writing | 129 | 128 |
Scores reflect capability match + benchmark data + pricing for each task. Methodology →