Model comparison
GPT-5.1-Codex vs Qwen3.5 397B-A17B
Qwen3.5 397B-A17B is the stronger model overall, scoring 46.0 to 38.6 on the Noometry Index.
Last verified . 1 shared benchmarks.
Alibaba (Qwen)Summary
- They share 1 benchmark with published results for both. GPT-5.1-Codex scores higher in 1 category and Qwen3.5 397B-A17B in 2 categories; 2 gaps are clear of the uncertainty.
- The widest gap is in math, where Qwen3.5 397B-A17B leads 46.1 to 30.3.
- Qwen3.5 397B-A17B is cheaper at $0.60 / $3.60 per million input/output tokens, against $1.25 / $10 for GPT-5.1-Codex.
- GPT-5.1-Codex accepts more context: 400K tokens versus 262K.
- Qwen3.5 397B-A17B has downloadable open weights; the other is API-only.
Side by side
| GPT-5.1-Codex | Qwen3.5 397B-A17B | |
|---|---|---|
| Provider | OpenAI | Alibaba (Qwen) |
| Noometry Index | 38.6 | 46.0 |
| Released | 2025-11-12 | 2026-02-01 |
| Weights | Proprietary | Open |
| Context window | 400K | 262K |
| Max output | 128K | 66K |
| Input $ / M tokens | $1.25 | $0.60 |
| Output $ / M tokens | $10 | $3.60 |
| Results tracked | 6 | 36 |
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Category by category
Coding Too close to call
GPT-5.1-Codex: 41.9 (#116), Qwen3.5 397B-A17B: 42.0 (#114)
| Benchmark | GPT-5.1-Codex | Qwen3.5 397B-A17B |
|---|---|---|
| LMArena WebDev | 1337 | 1400 |
| SWE-bench Verified (bash only) | 66% | — |
| LMArena Coding | — | 1465 |
| ALE-Bench | 1,245 | — |
Agentic & Tool Use GPT-5.1-Codex leads
GPT-5.1-Codex: 38.0 (#33), Qwen3.5 397B-A17B: 33.3 (#53)
| Benchmark | GPT-5.1-Codex | Qwen3.5 397B-A17B |
|---|---|---|
| Terminal-Bench | 60.4% | — |
| APEX-Agents | — | 24.9% |
| τ²-bench Airline | — | 81.5% |
| τ²-bench Banking | — | 9.8% |
| τ²-bench Retail | — | 84.4% |
| τ²-bench Telecom | — | 97.8% |
| METR Time Horizons | 70.8% | — |
Reasoning Not comparable
GPT-5.1-Codex: —, Qwen3.5 397B-A17B: 34.5 (#70)
| Benchmark | GPT-5.1-Codex | Qwen3.5 397B-A17B |
|---|---|---|
| Kagi LLM Benchmark | — | 73.7% |
| NYT Connections (extended) | — | 58.9% |
| Chess Puzzles | — | 13% |
| Thematic Generalization | — | 65.1% |
| LMArena Hard Prompts | — | 1448 |
| Mystery Game Puzzles | — | 18% |
| DTBench | — | 87.5% |
| LMCA | — | 37.9% |
| Epoch Capabilities Index | — | 146.65 |
Math Qwen3.5 397B-A17B leads
GPT-5.1-Codex: 30.3 (#235), Qwen3.5 397B-A17B: 46.1 (#73)
| Benchmark | GPT-5.1-Codex | Qwen3.5 397B-A17B |
|---|---|---|
| FrontierMath (Tiers 1-3) | — | 31.2% |
| OTIS Mock AIME 2024-2025 | — | 88.9% |
| ProofBench | 9% | — |
| LMArena Math | — | 1454 |
Knowledge Not comparable
GPT-5.1-Codex: —, Qwen3.5 397B-A17B: 53.3 (#58)
| Benchmark | GPT-5.1-Codex | Qwen3.5 397B-A17B |
|---|---|---|
| GPQA Diamond | — | 86.4% |
| LMArena Expert | — | 1462 |
Multimodal Not comparable
GPT-5.1-Codex: —, Qwen3.5 397B-A17B: 40.7 (#44)
| Benchmark | GPT-5.1-Codex | Qwen3.5 397B-A17B |
|---|---|---|
| LMArena Vision | — | 1263 |
Multilingual Not comparable
GPT-5.1-Codex: —, Qwen3.5 397B-A17B: 53.7 (#59)
| Benchmark | GPT-5.1-Codex | Qwen3.5 397B-A17B |
|---|---|---|
| LMArena Non-English | — | 1430 |
| LMArena Chinese | — | 1500 |
| LMArena French | — | 1461 |
| LMArena German | — | 1447 |
| LMArena Japanese | — | 1426 |
| LMArena Korean | — | 1384 |
| LMArena Russian | — | 1429 |
| LMArena Spanish | — | 1441 |
Instruction Following Not comparable
GPT-5.1-Codex: —, Qwen3.5 397B-A17B: 75.0 (#77)
| Benchmark | GPT-5.1-Codex | Qwen3.5 397B-A17B |
|---|---|---|
| LMArena Instruction Following | — | 1424 |
Long Context Not comparable
GPT-5.1-Codex: —, Qwen3.5 397B-A17B: 44.1 (#74)
| Benchmark | GPT-5.1-Codex | Qwen3.5 397B-A17B |
|---|---|---|
| LMArena Longer Query | — | 1442 |
Writing & Preference Not comparable
GPT-5.1-Codex: —, Qwen3.5 397B-A17B: 62.3 (#79)
| Benchmark | GPT-5.1-Codex | Qwen3.5 397B-A17B |
|---|---|---|
| LMArena Text | — | 1438 |
| LMArena Creative Writing | — | 1401 |
| EQ-Bench Creative Writing | — | 1478 |
| LMArena Multi-Turn | — | 1446 |
Frequently asked questions
Is GPT-5.1-Codex better than Qwen3.5 397B-A17B?
Qwen3.5 397B-A17B is the stronger model overall, scoring 46.0 to 38.6 on the Noometry Index.
Which is cheaper, GPT-5.1-Codex or Qwen3.5 397B-A17B?
Qwen3.5 397B-A17B is cheaper. It lists at $0.60 per million input tokens and $3.60 per million output tokens; GPT-5.1-Codex lists at $1.25 and $10.
Is GPT-5.1-Codex or Qwen3.5 397B-A17B better for coding?
They score almost the same on coding (41.9 vs 42.0); test both on your own repository before choosing.
Which has the bigger context window?
GPT-5.1-Codex does, with 400K tokens against 262K.
How many benchmarks do GPT-5.1-Codex and Qwen3.5 397B-A17B share?
1 benchmark has published results for both models. GPT-5.1-Codex has 6 scored results on Noometry and Qwen3.5 397B-A17B has 36.