# GPT-5.1-Codex vs Qwen3.5-9B

> GPT-5.1-Codex is the stronger model overall, scoring 38.6 to 33.8 on the Noometry Index. Qwen3.5-9B costs 31× less per token, which makes it the better buy when GPT-5.1-Codex's lead doesn't matter for your workload.

- Canonical page: https://noometry.com/compare/gpt-5-1-codex-vs-qwen3-5-9b
- 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 2 categories and Qwen3.5-9B in 1 category; 3 gaps are clear of the uncertainty.
- The widest gap is in agentic & tool use, where GPT-5.1-Codex leads 38.0 to 14.5.
- The biggest single-benchmark swing is Terminal-Bench: 60.4% for GPT-5.1-Codex and 9.2% for Qwen3.5-9B.
- Qwen3.5-9B is cheaper at $0.10 / $0.15 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.
- Qwen3.5-9B has downloadable open weights; the other is API-only.

## Snapshot

| | GPT-5.1-Codex | Qwen3.5-9B |
|---|---|---|
| Provider | OpenAI | Alibaba (Qwen) |
| Noometry Index | 38.6 | 33.8 |
| Rank | 186 | 236 |
| Context | 400K | 262K |
| Input $/M | $1.25 | $0.10 |
| Output $/M | $10 | $0.15 |
| Weights | Proprietary | Open |

## Coding

- GPT-5.1-Codex: 41.9 (#116)
- Qwen3.5-9B: 35.9 (#217)

| Benchmark | GPT-5.1-Codex | Qwen3.5-9B |
|---|---|---|
| SWE-bench Verified (bash only) | 66% | — |
| LMArena WebDev | 1337 | — |
| SciCode | — | 27.5% |
| ALE-Bench | 1,245 | — |

## Agentic & Tool Use

- GPT-5.1-Codex: 38.0 (#33)
- Qwen3.5-9B: 14.5 (#151)

| Benchmark | GPT-5.1-Codex | Qwen3.5-9B |
|---|---|---|
| Terminal-Bench | 60.4% | 9.2% |
| METR Time Horizons | 70.8% | — |

## Reasoning

- GPT-5.1-Codex: —
- Qwen3.5-9B: 23.1 (#182)

| Benchmark | GPT-5.1-Codex | Qwen3.5-9B |
|---|---|---|
| CritPt | — | 0.3% |
| Chess Puzzles | — | 12% |
| DTBench | — | 71.2% |
| LMCA | — | 24.5% |
| Epoch Capabilities Index | — | 139.46 |

## Math

- GPT-5.1-Codex: 30.3 (#235)
- Qwen3.5-9B: 34.8 (#192)

| Benchmark | GPT-5.1-Codex | Qwen3.5-9B |
|---|---|---|
| MathArena Final-Answer Competitions | — | 48.5% |
| OTIS Mock AIME 2024-2025 | — | 61.7% |
| ProofBench | 9% | — |

## Knowledge

- GPT-5.1-Codex: —
- Qwen3.5-9B: 46.0 (#84)

| Benchmark | GPT-5.1-Codex | Qwen3.5-9B |
|---|---|---|
| GPQA Diamond | — | 79% |

## FAQ

### Is GPT-5.1-Codex better than Qwen3.5-9B?

GPT-5.1-Codex is the stronger model overall, scoring 38.6 to 33.8 on the Noometry Index. Qwen3.5-9B costs 31× less per token, which makes it the better buy when GPT-5.1-Codex's lead doesn't matter for your workload.

### Which is cheaper, GPT-5.1-Codex or Qwen3.5-9B?

Qwen3.5-9B is cheaper. It lists at $0.10 per million input tokens and $0.15 per million output tokens; GPT-5.1-Codex lists at $1.25 and $10.

### Is GPT-5.1-Codex or Qwen3.5-9B better for coding?

GPT-5.1-Codex scores higher on coding benchmarks: 41.9 versus 35.9 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 Qwen3.5-9B share?

1 benchmark has published results for both models. GPT-5.1-Codex has 6 scored results on Noometry and Qwen3.5-9B has 10.