Model comparison
GPT-5.1-Codex-Max vs GPT-OSS 120B
Head-to-head evidence from 11 shared benchmark results across 5 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: GPT-5.1-Codex-Max #90 (Estimated); GPT-OSS 120B #116 (Supported). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. GPT-5.1-Codex-Max and GPT-OSS 120B share 11 comparable benchmark results. 0 of 8 categories are comparable. 2 results are unique to GPT-5.1-Codex-Max; 16 to GPT-OSS 120B.
Updated July 20, 2026- Shared results
- 11
- GPT-5.1-Codex-Max only
- 2
- GPT-OSS 120B only
- 16
- Comparable categories
- 0 / 8
Benchmark data for GPT-5.1-Codex-Max and GPT-OSS 120B is coming soon on BenchLM.
Confidence note. This is a partial-evidence comparison with 11 shared benchmark results across 5 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-Max is priced at $1.25 input / $10.00 output per 1M tokens, versus $0.00 input / $0.00 output per 1M tokens for GPT-OSS 120B. GPT-5.1-Codex-Max has the larger context window at 400K, compared with 128K for GPT-OSS 120B.
Category breakdown
Exact category averages are shown below. Not measured means BenchLM does not have enough sourced public coverage for that model and category.
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | GPT-5.1-Codex-Max | GPT-OSS 120B | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | GPT-5.1-Codex-Max$1.25 input / $10 output | GPT-OSS 120B$0 input / $0 output | GPT-OSS 120B has the lower combined listed price. |
| Generation speedtokens per second | GPT-5.1-Codex-MaxNot available | GPT-OSS 120B262 tok/s | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | GPT-5.1-Codex-MaxNot available | GPT-OSS 120B0.79 s | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | GPT-5.1-Codex-Max400K | GPT-OSS 120B128K | GPT-5.1-Codex-Max lists the larger context window. |
Benchmark Deep Dive
Agentic9 benchmarks
| Benchmark | GPT-5.1-Codex-Max | GPT-OSS 120B | Result |
|---|---|---|---|
| τ²-bench resultsSource | 83% | 65.8% | GPT-5.1-Codex-Max leads |
| AA Agentic IndexSource | — | 13.2% | Not comparable |
| APEX-Agents-AASource | — | 3.1% | Not comparable |
| GDPval-AASource | — | 15.0% | Not comparable |
| GDPval-AASource | — | 799 | Not comparable |
| Gert LabsSource | — | 29.61% | Not comparable |
| AA EnterpriseOps-GymSource | — | 25.5% | Not comparable |
| AA Harvey LABSource | — | 0.0% | Not comparable |
| AA ITBenchSource | — | 5.6% | Not comparable |
Coding5 benchmarks
Reasoning2 benchmarks
Knowledge8 benchmarks
| Benchmark | GPT-5.1-Codex-Max | GPT-OSS 120B | Result |
|---|---|---|---|
| Artificial Analysis Intelligence IndexSource | 34.7% | 23.8% | GPT-5.1-Codex-Max leads |
| AA-GPQA DiamondSource | 86.0% | 78.2% | GPT-5.1-Codex-Max leads |
| AA-HLESource | 23.4% | 18.5% | GPT-5.1-Codex-Max leads |
| AA-Omniscience IndexSource | -6.0% | -50.0% | GPT-5.1-Codex-Max leads |
| AA-Omniscience AccuracySource | 39.2% | 21.5% | GPT-5.1-Codex-Max leads |
| AA-Omniscience Hallucination RateSource | 74.4% | 91.2% | GPT-5.1-Codex-Max leads |
| AA Openness IndexSource | — | 38.9% | Not comparable |
| AA MMLU-ProSource | — | 80.8% | Not comparable |
Math1 benchmarks
| Benchmark | GPT-5.1-Codex-Max | GPT-OSS 120B | Result |
|---|---|---|---|
| AA AIME 2025Source | — | 93.4% | Not comparable |
Multilingual1 benchmarks
| Benchmark | GPT-5.1-Codex-Max | GPT-OSS 120B | Result |
|---|---|---|---|
| AA Global-MMLU-LiteSource | — | 82.8% | Not comparable |
Multimodal2 benchmarks
Inst. Following1 benchmarks
| Benchmark | GPT-5.1-Codex-Max | GPT-OSS 120B | Result |
|---|---|---|---|
| AA-IFBenchSource | 70.0% | 69.0% | GPT-5.1-Codex-Max leads |
Frequently Asked Questions (3)
Can I compare GPT-5.1-Codex-Max and GPT-OSS 120B 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-Max and GPT-OSS 120B today?
GPT-5.1-Codex-Max: $1.25 input / $10.00 output per 1M tokens GPT-OSS 120B: $0.00 input / $0.00 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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