Model comparison
Gemini 3.1 Pro Preview vs GPT-5-Codex
Gemini 3.1 Pro Preview is the stronger model overall, scoring 56.7 to 37.9 on the Noometry Index.
Last verified . 2 shared benchmarks.
GoogleSummary
- They share 2 benchmarks with published results for both. Gemini 3.1 Pro Preview scores higher in 3 categories and GPT-5-Codex in 0 categories; 2 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where Gemini 3.1 Pro Preview leads 71.7 to 30.9.
- The biggest single-benchmark swing is Terminal-Bench: 80.2% for Gemini 3.1 Pro Preview and 44.3% for GPT-5-Codex.
- GPT-5-Codex is cheaper at $1.25 / $10 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-Codex | |
|---|---|---|
| Provider | OpenAI | |
| Noometry Index | 56.7 | 37.9 |
| Released | 2026-02-19 | 2025-09-15 |
| Weights | Proprietary | Proprietary |
| Context window | 1.05M | 400K |
| Max output | 66K | 128K |
| Input $ / M tokens | $2 | $1.25 |
| Output $ / M tokens | $12 | $10 |
| Results tracked | 71 | 3 |
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Category by category
Coding Too close to call
Gemini 3.1 Pro Preview: 42.5 (#99), GPT-5-Codex: 42.4 (#103)
| Benchmark | Gemini 3.1 Pro Preview | GPT-5-Codex |
|---|---|---|
| WeirdML | 72.1% | 54.5% |
| SWE-bench Verified | 75.6% | — |
| DeepSWE | 11.7% | — |
| LMArena WebDev | 1447 | — |
| SciCode | 58.9% | — |
| GSO | 22.6% | — |
| LMArena Coding | 1484 | — |
| MirrorCode | 8.9% | — |
| ALE-Bench | 1,161 | — |
| AlgoTune | 2.02 | — |
Agentic & Tool Use Gemini 3.1 Pro Preview leads
Gemini 3.1 Pro Preview: 37.7 (#34), GPT-5-Codex: 31.0 (#72)
| Benchmark | Gemini 3.1 Pro Preview | GPT-5-Codex |
|---|---|---|
| Terminal-Bench | 80.2% | 44.3% |
| 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 Gemini 3.1 Pro Preview leads
Gemini 3.1 Pro Preview: 71.7 (#12), GPT-5-Codex: 30.9 (#83)
| Benchmark | Gemini 3.1 Pro Preview | GPT-5-Codex |
|---|---|---|
| ARC-AGI-2 | 77.1% | — |
| SimpleBench | 79.6% | — |
| Kagi LLM Benchmark | — | 70.3% |
| 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-Codex: —
| Benchmark | Gemini 3.1 Pro Preview | GPT-5-Codex |
|---|---|---|
| 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-Codex: —
| Benchmark | Gemini 3.1 Pro Preview | GPT-5-Codex |
|---|---|---|
| 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-Codex: —
| Benchmark | Gemini 3.1 Pro Preview | GPT-5-Codex |
|---|---|---|
| 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-Codex: —
| Benchmark | Gemini 3.1 Pro Preview | GPT-5-Codex |
|---|---|---|
| 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-Codex: —
| Benchmark | Gemini 3.1 Pro Preview | GPT-5-Codex |
|---|---|---|
| LMArena Instruction Following | 1466 | — |
Long Context Not comparable
Gemini 3.1 Pro Preview: 47.4 (#18), GPT-5-Codex: —
| Benchmark | Gemini 3.1 Pro Preview | GPT-5-Codex |
|---|---|---|
| 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-Codex: —
| Benchmark | Gemini 3.1 Pro Preview | GPT-5-Codex |
|---|---|---|
| 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-Codex?
Gemini 3.1 Pro Preview is the stronger model overall, scoring 56.7 to 37.9 on the Noometry Index.
Which is cheaper, Gemini 3.1 Pro Preview or GPT-5-Codex?
GPT-5-Codex is cheaper. It lists at $1.25 per million input tokens and $10 per million output tokens; Gemini 3.1 Pro Preview lists at $2 and $12.
Is Gemini 3.1 Pro Preview or GPT-5-Codex better for coding?
They score almost the same on coding (42.5 vs 42.4); test both on your own repository before choosing.
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-Codex share?
2 benchmarks have published results for both models. Gemini 3.1 Pro Preview has 71 scored results on Noometry and GPT-5-Codex has 3.