Google: Gemini 3.1 Pro Preview Custom Tools vs OpenAI: GPT-5.3-Codex
Side-by-side comparison of specs, pricing, benchmark scores, and task rankings. Updated 2026-11-07.
| Google: Gemini 3.1 Pro Preview Custom Tools | OpenAI: GPT-5.3-Codex | |
|---|---|---|
| Vendor | openai | |
| Quality Score | 100 | 100 |
| Benchmark Score | - | 73.4 |
| Input Price | $2.00/M | $1.75/M |
| Output Price | $12.00/M | $14.00/M |
| Context Window | 1,048,576 | 400,000 |
| Max Output | 65,536 | 128,000 |
| Tool Calling | ✓ | ✓ |
| Structured Output | ✓ | ✓ |
| Reasoning Mode | ✓ | ✓ |
| Vision | ✓ | ✓ |
| Audio | ✓ | - |
| Benchmark Scores | ||
| ai_index | - | 73.0 |
The verdict
For a sample job of 1 million input tokens and 250,000 output tokens, Gemini 3.1 Pro Preview Custom Tools costs $5.00 and GPT-5.3-Codex costs $5.25, so Gemini 3.1 Pro Preview Custom Tools is slightly cheaper 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 600 pages for GPT-5.3-Codex.
Only Gemini 3.1 Pro Preview Custom Tools offers audio input and video input.
Across the 20 tasks where they differ, Gemini 3.1 Pro Preview Custom Tools scores higher on 2 (JSON Extraction, Bulk Data Labeling), GPT-5.3-Codex on 18 (SQL Generation, Code Review, Code Completion and others).
Pick Gemini 3.1 Pro Preview Custom Tools if you need lower cost, long documents, audio input or video input; pick GPT-5.3-Codex if you need 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: Gemini 3.1 Pro Preview Custom Tools | OpenAI: GPT-5.3-Codex |
|---|---|---|
| SQL Generation | 132 | 141 |
| Code Review | 132 | 145 |
| Code Completion | 117 | 118 |
| Code Refactoring | 136 | 147 |
| Bug Fixing | 136 | 149 |
| Unit Test Generation | 124 | 132 |
| Code Documentation | 129 | 135 |
| Regex Writing | 117 | 124 |
| CI/CD Pipelines | 120 | 128 |
| Frontend Component Design | 122 | 130 |
| Data Analysis | 124 | 134 |
| CSV / Spreadsheet Cleanup | 132 | 135 |
| ETL Scripting | 128 | 138 |
| JSON Extraction | 121 | 120 |
| Bulk Data Labeling | 117 | 117 |
| OCR / Document Parsing | 131 | 134 |
| Table Extraction from PDFs | 131 | 134 |
| Long-Document Summarization | 136 | 148 |
| Short-Form Summarization | 113 | 116 |
| Blog Post Writing | 120 | 129 |
Scores reflect capability match + benchmark data + pricing for each task. Methodology →