# GPT-5.1-Codex vs Qwen3.5 Plus

> Side-by-side benchmark comparison for GPT-5.1-Codex and Qwen3.5 Plus across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/gpt-5-1-codex-vs-qwen3-5-plus
- Last updated: September 28, 2026

- Shared sourced benchmarks: 2
- HTML indexing: indexable
- Ranking lane: BenchAlign v5.7

## Quick Verdict

Evidence is too thin for a benchmark verdict: GPT-5.1-Codex and Qwen3.5 Plus share only 2 sourced benchmark rows.

## Summary

- Only 2 shared sourced benchmark rows are available. That is not enough for a broad capability verdict, so this mirror does not name an overall winner.
- Qwen3.5 Plus has the lower published output-token price.
- Qwen3.5 Plus has the larger published context window at 1M.

## Model Snapshot

| Property | GPT-5.1-Codex | Qwen3.5 Plus |
|----------|----------|----------|
| Creator | OpenAI | Alibaba |
| Type | Proprietary | Proprietary |
| Reasoning | Reasoning | Reasoning |
| Context | 400K | 1M |
| Independent public score (not head-to-head) | 44.6 | 48.92 |
| Benchmarks Covered | 4 | 4 |
| Pricing (input/output) | $1.25 / $10.00 | $0.40 / $2.40 |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- GPT-5.1-Codex public-lane score: Coming soon
- Qwen3.5 Plus public-lane score: Coming soon

| Benchmark | GPT-5.1-Codex | Qwen3.5 Plus | Winner |
|-----------|-----------|-----------|--------|
| Gert Labs | 49.68% | Coming soon | Coming soon |
| JobBench | 26.2% | 18.5% | GPT-5.1-Codex |

### Coding

- Winner: Insufficient shared evidence
- GPT-5.1-Codex public-lane score: 32.8 (Estimated · #84/142)
- Qwen3.5 Plus public-lane score: Coming soon

| Benchmark | GPT-5.1-Codex | Qwen3.5 Plus | Winner |
|-----------|-----------|-----------|--------|
| Vibe Code Bench | 13.12% | 15.74% | Qwen3.5 Plus |
| LiveCodeBench (Vals) | 85.6% | Coming soon | Coming soon |

### Reasoning

- Winner: Insufficient shared evidence
- GPT-5.1-Codex public-lane score: 69.9 (Unranked · 2 rankable rows)
- Qwen3.5 Plus public-lane score: Coming soon

### Multimodal & Grounded

- Winner: Insufficient shared evidence
- GPT-5.1-Codex public-lane score: 67.9 (Unranked · 1 rankable row)
- Qwen3.5 Plus public-lane score: Coming soon

### Knowledge

- Winner: Insufficient shared evidence
- GPT-5.1-Codex public-lane score: 48.4 (Estimated · #66/168)
- Qwen3.5 Plus public-lane score: Coming soon

### Instruction Following

- Winner: Insufficient shared evidence
- GPT-5.1-Codex public-lane score: 84.2 (#42/124)
- Qwen3.5 Plus public-lane score: Coming soon

### Mathematics

- Winner: Insufficient shared evidence
- GPT-5.1-Codex public-lane score: Coming soon
- Qwen3.5 Plus public-lane score: 39.3 (Unranked · 2 rankable rows)

| Benchmark | GPT-5.1-Codex | Qwen3.5 Plus | Winner |
|-----------|-----------|-----------|--------|
| FrontierMath v2 (Tiers 1-3) | Coming soon | 21.034% | Coming soon |
| FrontierMath v2 (Tier 4) | Coming soon | 2.083% | Coming soon |

## FAQ

### Is there enough evidence to pick between GPT-5.1-Codex and Qwen3.5 Plus?

Not yet. The models share only 2 sourced benchmark rows, so this mirror reports the available measurements and metadata without naming a broad winner.

### What can I compare safely on this page?

Published pricing, context windows, model type, and individual shared benchmark rows are directly comparable. Independent overall scores and non-overlapping benchmark coverage are labeled separately and should not be read as a controlled head-to-head result.

## Related Comparisons

- [GPT-5.1-Codex vs GPT-6 Astra](/compare/gpt-5-1-codex-vs-gpt-6-astra)
- [Qwen3.5 Plus vs GPT-6 Astra](/compare/gpt-6-astra-vs-qwen3-5-plus)
- [GPT-5.1-Codex vs Claude Opus 5.5](/compare/claude-opus-5-5-vs-gpt-5-1-codex)
- [Qwen3.5 Plus vs Claude Opus 5.5](/compare/claude-opus-5-5-vs-qwen3-5-plus)

## Explore More

- [GPT-5.1-Codex profile](/models/gpt-5-1-codex)
- [Qwen3.5 Plus profile](/models/qwen3-5-plus)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)