# GPT-5.1-Codex vs Qwen3.5 35B-A3B

> Qwen3.5 35B-A3B is the stronger model overall, scoring 42.0 to 38.6 on the Noometry Index.

- Canonical page: https://noometry.com/compare/gpt-5-1-codex-vs-qwen3-5-35b-a3b
- Last updated: 2026-10-12
- Shared benchmarks: 1

## Summary

- They share 1 benchmark with published results for both. GPT-5.1-Codex scores higher in 1 category and Qwen3.5 35B-A3B in 1 category; 2 gaps are clear of the uncertainty.
- The widest gap is in math, where Qwen3.5 35B-A3B leads 39.9 to 30.3.
- Qwen3.5 35B-A3B is cheaper at $0.25 / $2 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 35B-A3B has downloadable open weights; the other is API-only.

## Snapshot

| | GPT-5.1-Codex | Qwen3.5 35B-A3B |
|---|---|---|
| Provider | OpenAI | Alibaba (Qwen) |
| Noometry Index | 38.6 | 42.0 |
| Rank | 186 | 123 |
| Context | 400K | 262K |
| Input $/M | $1.25 | $0.25 |
| Output $/M | $10 | $2 |
| Weights | Proprietary | Open |

## Coding

- GPT-5.1-Codex: 41.9 (#116)
- Qwen3.5 35B-A3B: 33.8 (#251)

| Benchmark | GPT-5.1-Codex | Qwen3.5 35B-A3B |
|---|---|---|
| LMArena WebDev | 1337 | 1254 |
| SWE-bench Verified (bash only) | 66% | — |
| SciCode | — | 29.3% |
| LMArena Coding | — | 1410 |
| ALE-Bench | 1,245 | — |

## Agentic & Tool Use

- GPT-5.1-Codex: 38.0 (#33)
- Qwen3.5 35B-A3B: —

| Benchmark | GPT-5.1-Codex | Qwen3.5 35B-A3B |
|---|---|---|
| Terminal-Bench | 60.4% | — |
| METR Time Horizons | 70.8% | — |

## Reasoning

- GPT-5.1-Codex: —
- Qwen3.5 35B-A3B: 24.6 (#161)

| Benchmark | GPT-5.1-Codex | Qwen3.5 35B-A3B |
|---|---|---|
| CritPt | — | 0.6% |
| Chess Puzzles | — | 10% |
| LMArena Hard Prompts | — | 1400 |
| DTBench | — | 80% |
| LMCA | — | 29.5% |
| Epoch Capabilities Index | — | 142.52 |

## Math

- GPT-5.1-Codex: 30.3 (#235)
- Qwen3.5 35B-A3B: 39.9 (#97)

| Benchmark | GPT-5.1-Codex | Qwen3.5 35B-A3B |
|---|---|---|
| MathArena Final-Answer Competitions | — | 56% |
| OTIS Mock AIME 2024-2025 | — | 70% |
| ProofBench | 9% | — |
| LMArena Math | — | 1404 |

## Knowledge

- GPT-5.1-Codex: —
- Qwen3.5 35B-A3B: 47.8 (#79)

| Benchmark | GPT-5.1-Codex | Qwen3.5 35B-A3B |
|---|---|---|
| GPQA Diamond | — | 83.5% |
| Vectara Hallucination Rate | — | 10.5% |
| LMArena Expert | — | 1408 |

## Multilingual

- GPT-5.1-Codex: —
- Qwen3.5 35B-A3B: 50.0 (#127)

| Benchmark | GPT-5.1-Codex | Qwen3.5 35B-A3B |
|---|---|---|
| LMArena Non-English | — | 1378 |
| LMArena Chinese | — | 1457 |
| LMArena French | — | 1412 |
| LMArena German | — | 1367 |
| LMArena Japanese | — | 1325 |
| LMArena Korean | — | 1356 |
| LMArena Russian | — | 1376 |
| LMArena Spanish | — | 1392 |

## Instruction Following

- GPT-5.1-Codex: —
- Qwen3.5 35B-A3B: 72.8 (#128)

| Benchmark | GPT-5.1-Codex | Qwen3.5 35B-A3B |
|---|---|---|
| LMArena Instruction Following | — | 1379 |

## Long Context

- GPT-5.1-Codex: —
- Qwen3.5 35B-A3B: 42.4 (#127)

| Benchmark | GPT-5.1-Codex | Qwen3.5 35B-A3B |
|---|---|---|
| LMArena Longer Query | — | 1389 |

## Writing & Preference

- GPT-5.1-Codex: —
- Qwen3.5 35B-A3B: 57.9 (#124)

| Benchmark | GPT-5.1-Codex | Qwen3.5 35B-A3B |
|---|---|---|
| LMArena Text | — | 1395 |
| LMArena Creative Writing | — | 1346 |
| LMArena Multi-Turn | — | 1390 |

## FAQ

### Is GPT-5.1-Codex better than Qwen3.5 35B-A3B?

Qwen3.5 35B-A3B is the stronger model overall, scoring 42.0 to 38.6 on the Noometry Index.

### Which is cheaper, GPT-5.1-Codex or Qwen3.5 35B-A3B?

Qwen3.5 35B-A3B is cheaper. It lists at $0.25 per million input tokens and $2 per million output tokens; GPT-5.1-Codex lists at $1.25 and $10.

### Is GPT-5.1-Codex or Qwen3.5 35B-A3B better for coding?

GPT-5.1-Codex scores higher on coding benchmarks: 41.9 versus 33.8 in the Noometry coding category.

### 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 35B-A3B share?

1 benchmark has published results for both models. GPT-5.1-Codex has 6 scored results on Noometry and Qwen3.5 35B-A3B has 28.