Model comparison
Gemini 3.1 Pro Preview vs GPT-5.1-Codex-mini
Gemini 3.1 Pro Preview has enough public results to be ranked (#23); GPT-5.1-Codex-mini does not yet, so treat this comparison as directional.
Last verified . 2 shared benchmarks.
GoogleSummary
- They share 2 benchmarks with published results for both. Gemini 3.1 Pro Preview scores higher in 1 category and GPT-5.1-Codex-mini in 1 category; one gap is clear of the uncertainty.
- The widest gap is in coding, where Gemini 3.1 Pro Preview leads 42.5 to 31.6.
- The biggest single-benchmark swing is Terminal-Bench: 80.2% for Gemini 3.1 Pro Preview and 61.6% for GPT-5.1-Codex-mini.
- GPT-5.1-Codex-mini is cheaper at $0.25 / $2 per million input/output tokens, against $2 / $12 for Gemini 3.1 Pro Preview.
- Gemini 3.1 Pro Preview accepts more context: 1.05M tokens versus 400K.
Side by side
| Gemini 3.1 Pro Preview | GPT-5.1-Codex-mini | |
|---|---|---|
| Provider | OpenAI | |
| Noometry Index | 56.7 | 37.3 |
| Released | 2026-02-19 | 2025-11-12 |
| Weights | Proprietary | Proprietary |
| Context window | 1.05M | 400K |
| Max output | 66K | 128K |
| Input $ / M tokens | $2 | $0.25 |
| Output $ / M tokens | $12 | $2 |
| Results tracked | 71 | 2 |
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Category by category
Coding Gemini 3.1 Pro Preview leads
Gemini 3.1 Pro Preview: 42.5 (#99), GPT-5.1-Codex-mini: 31.6
| Benchmark | Gemini 3.1 Pro Preview | GPT-5.1-Codex-mini |
|---|---|---|
| LMArena WebDev | 1447 | 1244 |
| SWE-bench Verified | 75.6% | — |
| DeepSWE | 11.7% | — |
| SciCode | 58.9% | — |
| GSO | 22.6% | — |
| WeirdML | 72.1% | — |
| LMArena Coding | 1484 | — |
| MirrorCode | 8.9% | — |
| ALE-Bench | 1,161 | — |
| AlgoTune | 2.02 | — |
Agentic & Tool Use Too close to call
Gemini 3.1 Pro Preview: 37.7 (#34), GPT-5.1-Codex-mini: 38.5
| Benchmark | Gemini 3.1 Pro Preview | GPT-5.1-Codex-mini |
|---|---|---|
| Terminal-Bench | 80.2% | 61.6% |
| APEX-Agents | 35.3% | — |
| τ²-bench Banking | 26% | — |
| DeepResearch Bench | 47.8% | — |
| PostTrainBench | 22% | — |
| BALROG | 57% | — |
| ExploitBench | 26.1% | — |
| GBAEval | 0.8% | — |
| GDP.pdf | 17% | — |
| LMArena Search | 1211 | — |
| METR Time Horizons | 77% | — |
| Vending-Bench 2 | 3,774 | — |
Reasoning Not comparable
Gemini 3.1 Pro Preview: 71.7 (#12), GPT-5.1-Codex-mini: —
| Benchmark | Gemini 3.1 Pro Preview | GPT-5.1-Codex-mini |
|---|---|---|
| ARC-AGI-2 | 77.1% | — |
| SimpleBench | 79.6% | — |
| NYT Connections (extended) | 97.4% | — |
| ARC-AGI-1 | 98% | — |
| CritPt | 17.7% | — |
| Chess Puzzles | 55% | — |
| EnigmaEval | 36.8% | — |
| Thematic Generalization | 79.4% | — |
| EBR-Bench | 14.3% | — |
| LMArena Hard Prompts | 1485 | — |
| Mystery Game Puzzles | 34% | — |
| DTBench | 97.1% | — |
| LMCA | 53.8% | — |
| Epoch Capabilities Index | 154.77 | — |
| ForecastBench | 59 | — |
Math Not comparable
Gemini 3.1 Pro Preview: 62.1 (#34), GPT-5.1-Codex-mini: —
| Benchmark | Gemini 3.1 Pro Preview | GPT-5.1-Codex-mini |
|---|---|---|
| FrontierMath (Tiers 1-3) | 59.6% | — |
| FrontierMath Tier 4 | 26.8% | — |
| MathArena Final-Answer Competitions | 86.5% | — |
| OTIS Mock AIME 2024-2025 | 95.6% | — |
| ProofBench | 26% | — |
| LMArena Math | 1485 | — |
| FrontierMath (Feb 2025 set) | 36.9% | — |
| FrontierMath Tier 4 (v1) | 16.7% | — |
Knowledge Not comparable
Gemini 3.1 Pro Preview: 71.8 (#3), GPT-5.1-Codex-mini: —
| Benchmark | Gemini 3.1 Pro Preview | GPT-5.1-Codex-mini |
|---|---|---|
| GPQA Diamond | 94.4% | — |
| Humanity's Last Exam | 46.4% | — |
| SimpleQA Verified | 73.5% | — |
| Vectara Hallucination Rate | 10.4% | — |
| LMArena Expert | 1485 | — |
Multimodal Not comparable
Gemini 3.1 Pro Preview: 37.9 (#69), GPT-5.1-Codex-mini: —
| Benchmark | Gemini 3.1 Pro Preview | GPT-5.1-Codex-mini |
|---|---|---|
| LMArena Vision | 1296 | — |
| Blueprint-Bench 2 | 26.5% | — |
| Furniture Assembly | 26.7% | — |
| LMArena Document | 1444 | — |
Multilingual Not comparable
Gemini 3.1 Pro Preview: 57.0 (#12), GPT-5.1-Codex-mini: —
| Benchmark | Gemini 3.1 Pro Preview | GPT-5.1-Codex-mini |
|---|---|---|
| LMArena Non-English | 1477 | — |
| LMArena Chinese | 1529 | — |
| LMArena French | 1487 | — |
| LMArena German | 1491 | — |
| LMArena Japanese | 1493 | — |
| LMArena Korean | 1455 | — |
| LMArena Russian | 1498 | — |
| LMArena Spanish | 1479 | — |
Instruction Following Not comparable
Gemini 3.1 Pro Preview: 77.0 (#32), GPT-5.1-Codex-mini: —
| Benchmark | Gemini 3.1 Pro Preview | GPT-5.1-Codex-mini |
|---|---|---|
| LMArena Instruction Following | 1466 | — |
Long Context Not comparable
Gemini 3.1 Pro Preview: 47.4 (#18), GPT-5.1-Codex-mini: —
| Benchmark | Gemini 3.1 Pro Preview | GPT-5.1-Codex-mini |
|---|---|---|
| CL-bench | 20.8% | — |
| CL-bench Life | 16.9% | — |
| LMArena Longer Query | 1483 | — |
Writing & Preference Not comparable
Gemini 3.1 Pro Preview: 66.1 (#37), GPT-5.1-Codex-mini: —
| Benchmark | Gemini 3.1 Pro Preview | GPT-5.1-Codex-mini |
|---|---|---|
| LMArena Text | 1481 | — |
| LMArena Creative Writing | 1482 | — |
| EQ-Bench Creative Writing | 1491 | — |
| EQ-Bench 4 | 1142 | — |
| LMArena Multi-Turn | 1488 | — |
Frequently asked questions
Is Gemini 3.1 Pro Preview better than GPT-5.1-Codex-mini?
Gemini 3.1 Pro Preview has enough public results to be ranked (#23); GPT-5.1-Codex-mini does not yet, so treat this comparison as directional.
Which is cheaper, Gemini 3.1 Pro Preview or GPT-5.1-Codex-mini?
GPT-5.1-Codex-mini is cheaper. It lists at $0.25 per million input tokens and $2 per million output tokens; Gemini 3.1 Pro Preview lists at $2 and $12.
Is Gemini 3.1 Pro Preview or GPT-5.1-Codex-mini better for coding?
Gemini 3.1 Pro Preview scores higher on coding benchmarks: 42.5 versus 31.6 in the Noometry coding category.
Which has the bigger context window?
Gemini 3.1 Pro Preview does, with 1.05M tokens against 400K.
How many benchmarks do Gemini 3.1 Pro Preview and GPT-5.1-Codex-mini share?
2 benchmarks have published results for both models. Gemini 3.1 Pro Preview has 71 scored results on Noometry and GPT-5.1-Codex-mini has 2.