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BenchLM

Model comparison

Claude Opus 4.8 vs GPT-OSS 20B

Data verified

Head-to-head evidence from 17 shared benchmark results across 6 categories. Overall scores shown here use BenchLM's provisional ranking lane.

85/100
Margin
67.0pts
← winning
18/100
0 category wins0 category wins

Verified leaderboard positions: Claude Opus 4.8 #3; GPT-OSS 20B unranked

Evidence parity. Claude Opus 4.8 and GPT-OSS 20B share 17 comparable benchmark results. 0 of 8 categories are comparable. 36 results are unique to Claude Opus 4.8; 2 to GPT-OSS 20B.

Updated July 12, 2026
Shared results
17
Claude Opus 4.8 only
36
GPT-OSS 20B only
2
Comparable categories
0 / 8

Benchmark data for Claude Opus 4.8 and GPT-OSS 20B is coming soon on BenchLM.

Confidence note. This is a partial-evidence comparison with 17 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.

Claude Opus 4.8 is priced at $5.00 input / $25.00 output per 1M tokens, versus $0.00 input / $0.00 output per 1M tokens for GPT-OSS 20B. Claude Opus 4.8 has the larger context window at 1M, compared with 128K for GPT-OSS 20B.

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 scores and score margins for Claude Opus 4.8 and GPT-OSS 20B
CategoryClaude Opus 4.8ΔGPT-OSS 20B
AgenticClaude Opus 4.880.3MarginNo overlapGPT-OSS 20BNot measured
CodingClaude Opus 4.876.4MarginNo overlapGPT-OSS 20BNot measured
KnowledgeClaude Opus 4.862.7MarginNo overlapGPT-OSS 20BNot measured
MathClaude Opus 4.853.9MarginNo overlapGPT-OSS 20BNot measured
MultimodalClaude Opus 4.877.0MarginNo overlapGPT-OSS 20BNot measured

Operational comparison

Runtime and commercial metrics are compared only when both models have a complete sourced value.

MetricClaude Opus 4.8GPT-OSS 20BComparison
Input / output priceUSD per 1M tokensClaude Opus 4.8$5 input / $25 outputGPT-OSS 20B$0 input / $0 outputGPT-OSS 20B has the lower combined listed price.
Generation speedtokens per secondClaude Opus 4.8Not availableGPT-OSS 20B313 tok/sA complete speed comparison is not available.
First-answer latencyseconds to first tokenClaude Opus 4.8Not availableGPT-OSS 20B0.65 sA complete latency comparison is not available.
Context windowmaximum listed tokensClaude Opus 4.81MGPT-OSS 20B128KClaude Opus 4.8 lists the larger context window.

Benchmark Deep Dive

Agentic
BenchmarkClaude Opus 4.8GPT-OSS 20BResult
Terminal-Bench 2.0Source 74.6%—Not comparable
BrowseCompSource 84.3%—Not comparable
DeepSearchQASource 93.1%—Not comparable
OSWorld-VerifiedSource 83.4%—Not comparable
Finance Agent v2Source 53.9%—Not comparable
GDPval-AASource 1600554Claude Opus 4.8 leads
MCP AtlasSource 82.2%—Not comparable
ToolathlonSource 59.9%—Not comparable
Gert LabsSource 72.97%—Not comparable
AA Agentic IndexSource 47.2%3.1%Claude Opus 4.8 leads
Tau2-TelecomSource 94.4%60.2%Claude Opus 4.8 leads
GDPval-AASource 55.0%2.7%Claude Opus 4.8 leads
ResearchClawBenchSource 21.1%—Not comparable
OSWorld 2.0Source 20.6%—Not comparable
AA BriefcaseSource 1354—Not comparable
AA AutomationBenchSource 48.5%—Not comparable
AA EnterpriseOps-GymSource 44.0%—Not comparable
AA Harvey LABSource 7.5%—Not comparable
AA Tau3 BankingSource 27.6%—Not comparable
APEX-Agents-AASource —0.7%Not comparable
Coding
BenchmarkClaude Opus 4.8GPT-OSS 20BResult
SWE-bench VerifiedSource 88.6%—Not comparable
SWE-bench ProSource 69.2%—Not comparable
SWE MultilingualSource 84.4%—Not comparable
SWE MultimodalSource 38.4%—Not comparable
Terminal-Bench 2.0Source 74.6%—Not comparable
cursorBench31Source 58.4%—Not comparable
cursorBench32Source 62.3%—Not comparable
AA Coding IndexSource 74.3%20.7%Claude Opus 4.8 leads
Terminal-Bench HardSource 58.3%10.6%Claude Opus 4.8 leads
AA-SciCodeSource 53.5%34.4%Claude Opus 4.8 leads
FrontierCodeSource 46.5%—Not comparable
AA Terminal-Bench 2.1Source 84.6%—Not comparable
React Native EvalsSource —71%Not comparable
Reasoning
BenchmarkClaude Opus 4.8GPT-OSS 20BResult
AA-LCRSource 67.7%30.7%Claude Opus 4.8 leads
CritPtSource 20.9%1.4%Claude Opus 4.8 leads
Knowledge
BenchmarkClaude Opus 4.8GPT-OSS 20BResult
GPQASource 93.6%—Not comparable
GPQA-DSource 93.6%—Not comparable
HLESource 57.9%—Not comparable
HLE w/o toolsSource 49.8%—Not comparable
Artificial Analysis Intelligence IndexSource 55.7%14.9%Claude Opus 4.8 leads
AA-GPQA DiamondSource 92.0%68.8%Claude Opus 4.8 leads
AA-HLESource 45.7%9.8%Claude Opus 4.8 leads
AA-Omniscience IndexSource 27.4%-63.9%Claude Opus 4.8 leads
AA-Omniscience AccuracySource 46.6%15.5%Claude Opus 4.8 leads
AA-Omniscience Hallucination RateSource 35.9%94.1%Claude Opus 4.8 leads
Math
BenchmarkClaude Opus 4.8GPT-OSS 20BResult
USAMO 2026Source 96.7%—Not comparable
FrontierMath v2 (Tiers 1-3)Source 47.241%—Not comparable
FrontierMath v2 (Tier 4)Source 31.250%—Not comparable
Multilingual
BenchmarkClaude Opus 4.8GPT-OSS 20BResult
INCLUDESource 87.6%—Not comparable
Multimodal
BenchmarkClaude Opus 4.8GPT-OSS 20BResult
OfficeQA ProSource 66.2%—Not comparable
ScreenSpot ProSource 87.9%—Not comparable
CharXivSource 89.9%—Not comparable
CharXiv w/o toolsSource 80.5%—Not comparable
Design Arena WebsiteSource 1281895Claude Opus 4.8 leads
Inst. Following
BenchmarkClaude Opus 4.8GPT-OSS 20BResult
AA-IFBenchSource 62.2%65.1%GPT-OSS 20B leads
Frequently Asked Questions (3)

Can I compare Claude Opus 4.8 and GPT-OSS 20B 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 4.8 and GPT-OSS 20B today?

Claude Opus 4.8: $5.00 input / $25.00 output per 1M tokens GPT-OSS 20B: $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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Last updated: July 12, 2026

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