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Model comparison

Claude Opus 4.5 Thinking vs GPT-OSS 120B

Data verified

Head-to-head evidence from 14 shared benchmark results across 7 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.

57.44/100
Margin
7.4pts
← winning
50.08/100
0 category wins0 category wins

Public leaderboard positions: Claude Opus 4.5 Thinking #69 (Estimated); GPT-OSS 120B #116 (Supported). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.

Evidence parity. Claude Opus 4.5 Thinking and GPT-OSS 120B share 14 comparable benchmark results. 0 of 8 categories are comparable. 2 results are unique to Claude Opus 4.5 Thinking; 12 to GPT-OSS 120B.

Updated July 23, 2026
Shared results
14
Claude Opus 4.5 Thinking only
2
GPT-OSS 120B only
12
Comparable categories
0 / 8

Benchmark data for Claude Opus 4.5 Thinking and GPT-OSS 120B is coming soon on BenchLM.

Confidence note. This is a partial-evidence comparison with 14 shared benchmark results across 7 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.

Claude Opus 4.5 Thinking has the larger context window at 200K, 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.

MetricClaude Opus 4.5 ThinkingGPT-OSS 120BComparison
Input / output priceUSD per 1M tokensClaude Opus 4.5 ThinkingNot availableGPT-OSS 120B$0 input / $0 outputA complete price comparison is not available.
Generation speedtokens per secondClaude Opus 4.5 ThinkingNot availableGPT-OSS 120B262 tok/sA complete speed comparison is not available.
First-answer latencyseconds to first tokenClaude Opus 4.5 ThinkingNot availableGPT-OSS 120B0.79 sA complete latency comparison is not available.
Context windowmaximum listed tokensClaude Opus 4.5 Thinking200KGPT-OSS 120B128KClaude Opus 4.5 Thinking lists the larger context window.

Benchmark Deep Dive

Agentic
BenchmarkClaude Opus 4.5 ThinkingGPT-OSS 120BResult
τ²-bench resultsSource 89.5%65.8%Claude Opus 4.5 Thinking leads
AA Agentic IndexSource —13.2%Not comparable
APEX-Agents-AASource —3.1%Not comparable
GDPval-AASource —15.0%Not comparable
GDPval-AASource —799Not comparable
Gert LabsSource —29.61%Not comparable
AA EnterpriseOps-GymSource —25.5%Not comparable
AA ITBenchSource —5.6%Not comparable
Coding
BenchmarkClaude Opus 4.5 ThinkingGPT-OSS 120BResult
Vibe Code BenchSource 20.63%—Not comparable
AA-SciCodeSource 49.5%38.9%Claude Opus 4.5 Thinking leads
React Native EvalsSource —71.6%Not comparable
AA Coding IndexSource —30.4%Not comparable
AA LiveCodeBenchSource —87.8%Not comparable
Reasoning
BenchmarkClaude Opus 4.5 ThinkingGPT-OSS 120BResult
AA-LCRSource 74.0%50.7%Claude Opus 4.5 Thinking leads
CritPtSource 4.6%1.1%Claude Opus 4.5 Thinking leads
Knowledge
BenchmarkClaude Opus 4.5 ThinkingGPT-OSS 120BResult
Artificial Analysis Intelligence IndexSource 40.8%23.8%Claude Opus 4.5 Thinking leads
AA-GPQA DiamondSource 86.6%78.2%Claude Opus 4.5 Thinking leads
AA-HLESource 28.4%18.5%Claude Opus 4.5 Thinking leads
AA-Omniscience IndexSource 13.3%-50.0%Claude Opus 4.5 Thinking leads
AA-Omniscience AccuracySource 45.7%21.5%Claude Opus 4.5 Thinking leads
AA-Omniscience Hallucination RateSource 59.8%91.2%Claude Opus 4.5 Thinking leads
AA MMLU-ProSource 89.5%80.8%Claude Opus 4.5 Thinking leads
AA Openness IndexSource —38.9%Not comparable
Math
BenchmarkClaude Opus 4.5 ThinkingGPT-OSS 120BResult
AA AIME 2025Source —93.4%Not comparable
Multilingual
BenchmarkClaude Opus 4.5 ThinkingGPT-OSS 120BResult
AA Global-MMLU-LiteSource 91.3%82.8%Claude Opus 4.5 Thinking leads
Multimodal
BenchmarkClaude Opus 4.5 ThinkingGPT-OSS 120BResult
AA-MMMU-ProSource 74.0%—Not comparable
Design Arena WebsiteSource 1277998Claude Opus 4.5 Thinking leads
Inst. Following
BenchmarkClaude Opus 4.5 ThinkingGPT-OSS 120BResult
AA-IFBenchSource 58.0%69.0%GPT-OSS 120B leads
Frequently Asked Questions (3)

Can I compare Claude Opus 4.5 Thinking 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 Claude Opus 4.5 Thinking and GPT-OSS 120B today?

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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