Google: Gemma 4 31B (free) vs Google: Gemini 3.1 Pro Preview
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 | |
|---|---|---|
| Vendor | ||
| Quality Score | 100 | 100 |
| Benchmark Score | 53.7 | 74.7 |
| 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 | 76.7 |
| ai_index_agentic | 23.8 | 35.3 |
| ai_index_coding | 71.7 | 100.0 |
| eqbench | 57.5 | 64.7 |
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 costs $5.00, so Gemma 4 31B (free) is free for the same work.
Gemini 3.1 Pro Preview 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 offers audio input.
On our blended benchmark score Gemini 3.1 Pro Preview leads 74.7 to 53.7.
Across the 20 tasks where they differ, Gemma 4 31B (free) scores higher on 4 (Code Completion, JSON Extraction, Bulk Data Labeling and others), Gemini 3.1 Pro Preview on 16 (SQL Generation, Code Review, Code Refactoring and others).
Gemma 4 31B (free) was released in April 2026 and Gemini 3.1 Pro Preview in February 2026.
Pick Gemma 4 31B (free) if you need lower cost; pick Gemini 3.1 Pro Preview if you need long documents, audio input, benchmark performance 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 | Google: Gemma 4 31B (free) | Google: Gemini 3.1 Pro Preview |
|---|---|---|
| SQL Generation | 156 | 168 |
| Code Review | 152 | 168 |
| Code Completion | 131 | 120 |
| Code Refactoring | 151 | 168 |
| Bug Fixing | 160 | 177 |
| Unit Test Generation | 143 | 154 |
| Code Documentation | 137 | 144 |
| Regex Writing | 131 | 133 |
| CI/CD Pipelines | 135 | 145 |
| Frontend Component Design | 138 | 145 |
| Data Analysis | 152 | 164 |
| CSV / Spreadsheet Cleanup | 145 | 155 |
| ETL Scripting | 143 | 156 |
| JSON Extraction | 143 | 137 |
| Bulk Data Labeling | 133 | 123 |
| OCR / Document Parsing | 140 | 147 |
| Table Extraction from PDFs | 140 | 147 |
| Long-Document Summarization | 149 | 163 |
| Short-Form Summarization | 129 | 121 |
| Blog Post Writing | 133 | 140 |
Scores reflect capability match + benchmark data + pricing for each task. Methodology →