# GPT-5.1-Codex vs Qwen3.5 Plus

> Qwen3.5 Plus is the stronger model overall, scoring 42.9 to 38.6 on the Noometry Index.

- Canonical page: https://noometry.com/compare/gpt-5-1-codex-vs-qwen3-5-plus
- 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 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 49.6 to 30.3.
- 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.

## Snapshot

| | GPT-5.1-Codex | Qwen3.5 Plus |
|---|---|---|
| Provider | OpenAI | Alibaba (Qwen) |
| Noometry Index | 38.6 | 42.9 |
| Rank | 186 | 106 |
| Context | 400K | 1M |
| Input $/M | $1.25 | $0.40 |
| Output $/M | $10 | $2.40 |
| Weights | Proprietary | Proprietary |

## Coding

- GPT-5.1-Codex: 41.9 (#116)
- 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

- GPT-5.1-Codex: 38.0 (#33)
- 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

- GPT-5.1-Codex: —
- Qwen3.5 Plus: 32.8 (#74)

| Benchmark | GPT-5.1-Codex | Qwen3.5 Plus |
|---|---|---|
| Chess Puzzles | — | 22% |
| Mystery Game Puzzles | — | 17% |
| DTBench | — | 80.5% |
| LMCA | — | 36.4% |
| Epoch Capabilities Index | — | 146.78 |

## Math

- GPT-5.1-Codex: 30.3 (#235)
- Qwen3.5 Plus: 49.6 (#61)

| 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

- GPT-5.1-Codex: —
- Qwen3.5 Plus: 46.0 (#83)

| Benchmark | GPT-5.1-Codex | Qwen3.5 Plus |
|---|---|---|
| GPQA Diamond | — | 84.8% |
| SimpleQA Verified | — | 25.4% |
| Vectara Hallucination Rate | — | 10.7% |

## Long Context

- GPT-5.1-Codex: —
- Qwen3.5 Plus: 43.0 (#113)

| Benchmark | GPT-5.1-Codex | Qwen3.5 Plus |
|---|---|---|
| CL-bench | — | 19.8% |
| CL-bench Life | — | 12.4% |

## FAQ

### Is GPT-5.1-Codex better than Qwen3.5 Plus?

Qwen3.5 Plus is the stronger model overall, scoring 42.9 to 38.6 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.