Model comparison
GPT-5.1-Codex vs Qwen3.5 Plus
Head-to-head evidence from 2 shared benchmark results across 2 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: GPT-5.1-Codex #99 (Estimated); Qwen3.5 Plus #138 (Estimated). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. GPT-5.1-Codex and Qwen3.5 Plus share 2 comparable benchmark results. 0 of 8 categories are comparable. 14 results are unique to GPT-5.1-Codex; 2 to Qwen3.5 Plus.
Updated July 23, 2026- Shared results
- 2
- GPT-5.1-Codex only
- 14
- Qwen3.5 Plus only
- 2
- Comparable categories
- 0 / 8
Benchmark data for GPT-5.1-Codex and Qwen3.5 Plus is coming soon on BenchLM.
Confidence note. This is a partial-evidence comparison with 2 shared benchmark results across 2 evidence categories; 0 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.
Why this result
BenchLM has partial data for these models, but not enough overlapping benchmark coverage to produce a fair score-level comparison yet.
Qwen3.5 Plus has the larger context window at 1M, compared with 400K for GPT-5.1-Codex.
Category breakdown
Exact category averages are shown below. Not measured means BenchLM does not have enough sourced public coverage for that model and category.
| Category | GPT-5.1-Codex | Δ | Qwen3.5 Plus |
|---|---|---|---|
| Math | GPT-5.1-CodexNot measured | MarginNo overlap | Qwen3.5 Plus16.3 |
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | GPT-5.1-Codex | Qwen3.5 Plus | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | GPT-5.1-CodexNot available | Qwen3.5 Plus$0.4 input / $2.4 output | A complete price comparison is not available. |
| Generation speedtokens per second | GPT-5.1-CodexNot available | Qwen3.5 PlusNot available | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | GPT-5.1-CodexNot available | Qwen3.5 PlusNot available | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | GPT-5.1-Codex400K | Qwen3.5 Plus1M | Qwen3.5 Plus lists the larger context window. |
Benchmark Deep Dive
Agentic3 benchmarks
Coding2 benchmarks
Reasoning2 benchmarks
Knowledge6 benchmarks
| Benchmark | GPT-5.1-Codex | Qwen3.5 Plus | Result |
|---|---|---|---|
| Artificial Analysis Intelligence IndexSource | 34.7% | — | Not comparable |
| AA-GPQA DiamondSource | 86.0% | — | Not comparable |
| AA-HLESource | 23.4% | — | Not comparable |
| AA-Omniscience IndexSource | -6.0% | — | Not comparable |
| AA-Omniscience AccuracySource | 39.2% | — | Not comparable |
| AA-Omniscience Hallucination RateSource | 74.4% | — | Not comparable |
Math2 benchmarks
Multimodal2 benchmarks
Inst. Following1 benchmarks
| Benchmark | GPT-5.1-Codex | Qwen3.5 Plus | Result |
|---|---|---|---|
| AA-IFBenchSource | 70.0% | — | Not comparable |
Frequently Asked Questions (3)
Can I compare GPT-5.1-Codex and Qwen3.5 Plus on BenchLM yet?
Not fully yet. BenchLM is tracking both models, but the sourced benchmark breakdown for this comparison is still coming soon.
Why does this comparison show “coming soon”?
BenchLM only shows category winners and benchmark-level calls when we have sourced results that can be compared fairly. For these models, the public benchmark coverage is not complete enough yet.
What data is available for GPT-5.1-Codex and Qwen3.5 Plus today?
Qwen3.5 Plus: $0.40 input / $2.40 output per 1M tokens Both model pages still include creator, context window, reasoning mode, and other metadata while benchmark coverage fills in.
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