Model comparison
GPT-5.2-Codex vs GPT-OSS 120B
Head-to-head evidence from 12 shared benchmark results across 5 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: GPT-5.2-Codex #58 (Supported); GPT-OSS 120B #116 (Supported). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. GPT-5.2-Codex and GPT-OSS 120B share 12 comparable benchmark results. 0 of 8 categories are comparable. 3 results are unique to GPT-5.2-Codex; 15 to GPT-OSS 120B.
Updated July 20, 2026- Shared results
- 12
- GPT-5.2-Codex only
- 3
- GPT-OSS 120B only
- 15
- Comparable categories
- 0 / 8
Benchmark data for GPT-5.2-Codex and GPT-OSS 120B is coming soon on BenchLM.
Confidence note. This is a partial-evidence comparison with 12 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-5.2-Codex is priced at $1.75 input / $14.00 output per 1M tokens, versus $0.00 input / $0.00 output per 1M tokens for GPT-OSS 120B. GPT-5.2-Codex 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-5.2-Codex | GPT-OSS 120B | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | GPT-5.2-Codex$1.75 input / $14 output | GPT-OSS 120B$0 input / $0 output | GPT-OSS 120B has the lower combined listed price. |
| Generation speedtokens per second | GPT-5.2-Codex123 tok/s | GPT-OSS 120B262 tok/s | GPT-OSS 120B has the higher measured throughput. |
| First-answer latencyseconds to first token | GPT-5.2-Codex87.34 s | GPT-OSS 120B0.79 s | GPT-OSS 120B reaches the first token sooner. |
| Context windowmaximum listed tokens | GPT-5.2-Codex400K | GPT-OSS 120B128K | GPT-5.2-Codex lists the larger context window. |
Benchmark Deep Dive
Agentic10 benchmarks
| Benchmark | GPT-5.2-Codex | GPT-OSS 120B | Result |
|---|---|---|---|
| τ²-bench resultsSource | 92.1% | 65.8% | GPT-5.2-Codex leads |
| Gert LabsSource | 51.79% | 29.61% | GPT-5.2-Codex leads |
| JobBenchSource | 26.0% | — | Not comparable |
| 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 |
| 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-5.2-Codex | GPT-OSS 120B | Result |
|---|---|---|---|
| Artificial Analysis Intelligence IndexSource | 40.1% | 23.8% | GPT-5.2-Codex leads |
| AA-GPQA DiamondSource | 89.9% | 78.2% | GPT-5.2-Codex leads |
| AA-HLESource | 33.5% | 18.5% | GPT-5.2-Codex leads |
| AA-Omniscience IndexSource | -2.5% | -50.0% | GPT-5.2-Codex leads |
| AA-Omniscience AccuracySource | 40.7% | 21.5% | GPT-5.2-Codex leads |
| AA-Omniscience Hallucination RateSource | 72.8% | 91.2% | GPT-5.2-Codex leads |
| AA Openness IndexSource | — | 38.9% | Not comparable |
| AA MMLU-ProSource | — | 80.8% | Not comparable |
Math1 benchmarks
| Benchmark | GPT-5.2-Codex | GPT-OSS 120B | Result |
|---|---|---|---|
| AA AIME 2025Source | — | 93.4% | Not comparable |
Multilingual1 benchmarks
| Benchmark | GPT-5.2-Codex | GPT-OSS 120B | Result |
|---|---|---|---|
| AA Global-MMLU-LiteSource | — | 82.8% | Not comparable |
Multimodal2 benchmarks
Inst. Following1 benchmarks
| Benchmark | GPT-5.2-Codex | GPT-OSS 120B | Result |
|---|---|---|---|
| AA-IFBenchSource | 77.6% | 69.0% | GPT-5.2-Codex leads |
Frequently Asked Questions (3)
Can I compare GPT-5.2-Codex 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-5.2-Codex and GPT-OSS 120B today?
GPT-5.2-Codex: $1.75 input / $14.00 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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