Google: Gemma 4 31B (free) vs Google: Gemini 3.1 Pro Preview Custom Tools
Side-by-side comparison of specs, pricing, benchmark scores, and task rankings. Updated 2026-11-07.
| Google: Gemma 4 31B (free) | Google: Gemini 3.1 Pro Preview Custom Tools | |
|---|---|---|
| Vendor | ||
| Quality Score | 100 | 100 |
| Benchmark Score | 53.7 | - |
| Input Price | Free | $2.00/M |
| Output Price | Free | $12.00/M |
| Context Window | 262,144 | 1,048,576 |
| Max Output | 32,768 | 65,536 |
| Tool Calling | ✓ | ✓ |
| Structured Output | ✓ | ✓ |
| Reasoning Mode | ✓ | ✓ |
| Vision | ✓ | ✓ |
| Audio | - | ✓ |
| Benchmark Scores | ||
| ai_index | 48.4 | - |
| ai_index_agentic | 23.8 | - |
| ai_index_coding | 71.7 | - |
| eqbench | 57.5 | - |
The verdict
For a sample job of 1 million input tokens and 250,000 output tokens, Gemma 4 31B (free) costs $0 and Gemini 3.1 Pro Preview Custom Tools costs $5.00, so Gemma 4 31B (free) is free for the same work.
Gemini 3.1 Pro Preview Custom Tools reads up to 1,048,576 tokens at once, roughly 1,573 pages of text, against about 393 pages for Gemma 4 31B (free).
Only Gemini 3.1 Pro Preview Custom Tools offers audio input.
Across the 20 tasks where they differ, Gemma 4 31B (free) scores higher on 20 (SQL Generation, Code Review, Code Completion and others).
Gemma 4 31B (free) was released in April 2026 and Gemini 3.1 Pro Preview Custom Tools in February 2026.
Pick Gemma 4 31B (free) if you need lower cost or the stronger all-round task scores; pick Gemini 3.1 Pro Preview Custom Tools if you need long documents or audio 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 | Google: Gemma 4 31B (free) | Google: Gemini 3.1 Pro Preview Custom Tools |
|---|---|---|
| SQL Generation | 156 | 132 |
| Code Review | 152 | 132 |
| Code Completion | 131 | 117 |
| Code Refactoring | 151 | 136 |
| Bug Fixing | 160 | 136 |
| Unit Test Generation | 143 | 124 |
| Code Documentation | 137 | 129 |
| Regex Writing | 131 | 117 |
| CI/CD Pipelines | 135 | 120 |
| Frontend Component Design | 138 | 122 |
| Data Analysis | 152 | 124 |
| CSV / Spreadsheet Cleanup | 145 | 132 |
| ETL Scripting | 143 | 128 |
| JSON Extraction | 143 | 121 |
| Bulk Data Labeling | 133 | 117 |
| OCR / Document Parsing | 140 | 131 |
| Table Extraction from PDFs | 140 | 131 |
| Long-Document Summarization | 149 | 136 |
| Short-Form Summarization | 129 | 113 |
| Blog Post Writing | 133 | 120 |
Scores reflect capability match + benchmark data + pricing for each task. Methodology →