Model comparison
GPT-5.1-Codex vs Qwen3.5 Plus
Qwen3.5 Plus is the stronger model overall, scoring 42.3 to 38.2 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 0 categories and Qwen3.5 Plus in 1 category; one gap is clear of the uncertainty.
- The widest gap is in math, where Qwen3.5 Plus leads 47.9 to 29.3.
- Qwen3.5 Plus is cheaper at $0.40 / $2.40 per million input/output tokens, against $1.25 / $10 for GPT-5.1-Codex.
- Qwen3.5 Plus accepts more context: 1M tokens versus 400K.
Side by side
| GPT-5.1-Codex | Qwen3.5 Plus | |
|---|---|---|
| Provider | OpenAI | Alibaba (Qwen) |
| Noometry Index | 38.2 | 42.3 |
| Released | 2025-11-12 | 2026-02-16 |
| Weights | Proprietary | Proprietary |
| Context window | 400K | 1M |
| Max output | 128K | 66K |
| Input $ / M tokens | $1.25 | $0.40 |
| Output $ / M tokens | $10 | $2.40 |
| Results tracked | 6 | 15 |
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Category by category
Coding Not comparable
GPT-5.1-Codex: 41.7 (#107), Qwen3.5 Plus: —
| Benchmark | GPT-5.1-Codex | Qwen3.5 Plus |
|---|---|---|
| ALE-Bench | 1,245 | 621.92 |
| SWE-bench Verified (bash only) | 66% | — |
| LMArena WebDev | 1337 | — |
Agentic & Tool Use Not comparable
GPT-5.1-Codex: 37.8 (#32), Qwen3.5 Plus: —
| Benchmark | GPT-5.1-Codex | Qwen3.5 Plus |
|---|---|---|
| Terminal-Bench | 60.4% | — |
| METR Time Horizons | 70.8% | — |
| Vending-Bench 2 | — | 0.54 |
Reasoning Not comparable
GPT-5.1-Codex: —, Qwen3.5 Plus: 32.0 (#67)
| Benchmark | GPT-5.1-Codex | Qwen3.5 Plus |
|---|---|---|
| Chess Puzzles | — | 22% |
| Mystery Game Puzzles | — | 17% |
| DTBench | — | 80.5% |
| LMCA | — | 36.4% |
| Epoch Capabilities Index | — | 146.79 |
Math Qwen3.5 Plus leads
GPT-5.1-Codex: 29.3 (#218), Qwen3.5 Plus: 47.9 (#55)
| Benchmark | GPT-5.1-Codex | Qwen3.5 Plus |
|---|---|---|
| OTIS Mock AIME 2024-2025 | — | 86.7% |
| ProofBench | 9% | — |
| FrontierMath (Feb 2025 set) | — | 21% |
| FrontierMath Tier 4 (v1) | — | 2.1% |
Knowledge Not comparable
GPT-5.1-Codex: —, Qwen3.5 Plus: 46.0 (#78)
| Benchmark | GPT-5.1-Codex | Qwen3.5 Plus |
|---|---|---|
| GPQA Diamond | — | 84.8% |
| SimpleQA Verified | — | 25.4% |
| Vectara Hallucination Rate | — | 10.7% |
Long Context Not comparable
GPT-5.1-Codex: —, Qwen3.5 Plus: 42.9 (#109)
| Benchmark | GPT-5.1-Codex | Qwen3.5 Plus |
|---|---|---|
| CL-bench | — | 19.8% |
| CL-bench Life | — | 12.4% |
Frequently asked questions
Is GPT-5.1-Codex better than Qwen3.5 Plus?
Qwen3.5 Plus is the stronger model overall, scoring 42.3 to 38.2 on the Noometry Index.
Which is cheaper, GPT-5.1-Codex or Qwen3.5 Plus?
Qwen3.5 Plus is cheaper. It lists at $0.40 per million input tokens and $2.40 per million output tokens; GPT-5.1-Codex lists at $1.25 and $10.
Which has the bigger context window?
Qwen3.5 Plus does, with 1M tokens against 400K.
How many benchmarks do GPT-5.1-Codex and Qwen3.5 Plus share?
1 benchmark has published results for both models. GPT-5.1-Codex has 6 scored results on Noometry and Qwen3.5 Plus has 15.