Model comparison
GPT-5.1-Codex vs Qwen3.5 397B
Head-to-head evidence from 13 shared benchmark results across 6 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: GPT-5.1-Codex #99 (Estimated); Qwen3.5 397B #71 (Estimated). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. GPT-5.1-Codex and Qwen3.5 397B share 13 comparable benchmark results. 0 of 8 categories are comparable. 3 results are unique to GPT-5.1-Codex; 42 to Qwen3.5 397B.
Updated July 23, 2026- Shared results
- 13
- GPT-5.1-Codex only
- 3
- Qwen3.5 397B only
- 42
- Comparable categories
- 0 / 8
Benchmark data for GPT-5.1-Codex and Qwen3.5 397B is coming soon on BenchLM.
Confidence note. This is a partial-evidence comparison with 13 shared benchmark results across 6 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.
GPT-5.1-Codex has the larger context window at 400K, compared with 128K for Qwen3.5 397B.
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 397B |
|---|---|---|---|
| Agentic | GPT-5.1-CodexNot measured | MarginNo overlap | Qwen3.5 397B56.5 |
| Coding | GPT-5.1-CodexNot measured | MarginNo overlap | Qwen3.5 397B66.5 |
| Reasoning | GPT-5.1-CodexNot measured | MarginNo overlap | Qwen3.5 397B63.2 |
| Knowledge | GPT-5.1-CodexNot measured | MarginNo overlap | Qwen3.5 397B56.6 |
| Math | GPT-5.1-CodexNot measured | MarginNo overlap | Qwen3.5 397B90.6 |
| Multilingual | GPT-5.1-CodexNot measured | MarginNo overlap | Qwen3.5 397B84.7 |
| Multimodal | GPT-5.1-CodexNot measured | MarginNo overlap | Qwen3.5 397B79.6 |
| Inst. Following | GPT-5.1-CodexNot measured | MarginNo overlap | Qwen3.5 397B92.6 |
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | GPT-5.1-Codex | Qwen3.5 397B | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | GPT-5.1-CodexNot available | Qwen3.5 397B$0.6 input / $3.6 output | A complete price comparison is not available. |
| Generation speedtokens per second | GPT-5.1-CodexNot available | Qwen3.5 397B96 tok/s | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | GPT-5.1-CodexNot available | Qwen3.5 397B2.44 s | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | GPT-5.1-Codex400K | Qwen3.5 397B128K | GPT-5.1-Codex lists the larger context window. |
Benchmark Deep Dive
Agentic19 benchmarks
| Benchmark | GPT-5.1-Codex | Qwen3.5 397B | Result |
|---|---|---|---|
| τ²-bench resultsSource | 83% | 95.6% | Qwen3.5 397B leads |
| Gert LabsSource | 49.68% | 46.76% | GPT-5.1-Codex leads |
| JobBenchSource | 26.2% | — | Not comparable |
| Terminal-Bench 2.0Source | — | 52.5% | Not comparable |
| BrowseCompSource | — | 62% | Not comparable |
| Claw-EvalSource | — | 56.8% | Not comparable |
| QwenClawBenchSource | — | 51.8% | Not comparable |
| τ³-bench resultsSource | — | 68.4% | Not comparable |
| VITA-BenchSource | — | 43.7% | Not comparable |
| DeepPlanningSource | — | 37.6% | Not comparable |
| ToolathlonSource | — | 36.3% | Not comparable |
| MCP AtlasSource | — | 46.1% | Not comparable |
| MCP-TasksSource | — | 74.2% | Not comparable |
| WideResearchSource | — | 74.0% | Not comparable |
| ResearchClawBenchSource | — | 14.2% | Not comparable |
| AA Agentic IndexSource | — | 19.9% | Not comparable |
| APEX-Agents-AASource | — | 15.3% | Not comparable |
| GDPval-AASource | — | 23.1% | Not comparable |
| GDPval-AASource | — | 962 | Not comparable |
Coding6 benchmarks
Reasoning4 benchmarks
Knowledge12 benchmarks
| Benchmark | GPT-5.1-Codex | Qwen3.5 397B | Result |
|---|---|---|---|
| Artificial Analysis Intelligence IndexSource | 34.7% | 33.7% | GPT-5.1-Codex leads |
| AA-GPQA DiamondSource | 86.0% | 89.3% | Qwen3.5 397B leads |
| AA-HLESource | 23.4% | 27.3% | Qwen3.5 397B leads |
| AA-Omniscience IndexSource | -6.0% | -29.8% | GPT-5.1-Codex leads |
| AA-Omniscience AccuracySource | 39.2% | 31.4% | GPT-5.1-Codex leads |
| AA-Omniscience Hallucination RateSource | 74.4% | 89.1% | GPT-5.1-Codex leads |
| GPQASource | — | 88.4% | Not comparable |
| SuperGPQASource | — | 70.4% | Not comparable |
| MMLU-ProSource | — | 87.8% | Not comparable |
| MMLU-ReduxSource | — | 94.9% | Not comparable |
| C-EvalSource | — | 93% | Not comparable |
| HLESource | — | 28.7% | Not comparable |
Math5 benchmarks
Multilingual2 benchmarks
Multimodal8 benchmarks
| Benchmark | GPT-5.1-Codex | Qwen3.5 397B | Result |
|---|---|---|---|
| AA-MMMU-ProSource | 72.5% | 77.3% | Qwen3.5 397B leads |
| Design Arena WebsiteSource | 1191 | — | Not comparable |
| MMMU-ProSource | — | 79% | Not comparable |
| MathVisionSource | — | 88.6% | Not comparable |
| CharXivSource | — | 80.8% | Not comparable |
| VideoMMMUSource | — | 84.7% | Not comparable |
| ScreenSpot ProSource | — | 65.6% | Not comparable |
| V*Source | — | 95.8% | Not comparable |
Frequently Asked Questions (3)
Can I compare GPT-5.1-Codex and Qwen3.5 397B 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 397B today?
Qwen3.5 397B: $0.60 input / $3.60 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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