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Model comparison

Claude Mythos 5 vs GPT-OSS 20B

Data verified

Head-to-head evidence from 0 shared benchmark results across 0 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.

No sourced benchmark result is currently shared by both models. This page therefore compares only the available metadata, pricing, and runtime rows; it does not name a quality winner.
83.93/100
Margin
41.2pts
← winning
42.74/100
0 category wins0 category wins

Public leaderboard positions: Claude Mythos 5 #1 (Supported); GPT-OSS 20B #159 (Supported). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.

Evidence parity. Claude Mythos 5 and GPT-OSS 20B share 0 comparable benchmark results. 0 of 8 categories are comparable. 15 results are unique to Claude Mythos 5; 18 to GPT-OSS 20B.

Updated July 23, 2026
Shared results
0
Claude Mythos 5 only
15
GPT-OSS 20B only
18
Comparable categories
0 / 8

Benchmark data for Claude Mythos 5 and GPT-OSS 20B is coming soon on BenchLM.

Confidence note. This is a partial-evidence comparison with 0 shared benchmark results across 0 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 Mythos 5 is priced at $10.00 input / $50.00 output per 1M tokens, versus $0.00 input / $0.00 output per 1M tokens for GPT-OSS 20B. Claude Mythos 5 has the larger context window at 1M+, compared with 128K for GPT-OSS 20B.

Operational comparison

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

MetricClaude Mythos 5GPT-OSS 20BComparison
Input / output priceUSD per 1M tokensClaude Mythos 5$10 input / $50 outputGPT-OSS 20B$0 input / $0 outputGPT-OSS 20B has the lower combined listed price.
Generation speedtokens per secondClaude Mythos 5Not availableGPT-OSS 20B313 tok/sA complete speed comparison is not available.
First-answer latencyseconds to first tokenClaude Mythos 5Not availableGPT-OSS 20B0.65 sA complete latency comparison is not available.
Context windowmaximum listed tokensClaude Mythos 51M+GPT-OSS 20B128KClaude Mythos 5 lists the larger context window.

Benchmark Deep Dive

Agentic
BenchmarkClaude Mythos 5GPT-OSS 20BResult
Terminal-Bench 2.0Source 88%—Not comparable
OSWorld-VerifiedSource 85%—Not comparable
BrowseCompSource 88%—Not comparable
ExploitGymSource 17.5%—Not comparable
AA Agentic IndexSource —3.1%Not comparable
APEX-Agents-AASource —0.7%Not comparable
τ²-bench resultsSource —60.2%Not comparable
GDPval-AASource —3.0%Not comparable
GDPval-AASource —559Not comparable
Coding
BenchmarkClaude Mythos 5GPT-OSS 20BResult
SWE-bench VerifiedSource 95.5%—Not comparable
SWE-bench ProSource 80.3%—Not comparable
Terminal-Bench 2.0Source 88.0%—Not comparable
React Native EvalsSource —71%Not comparable
AA Coding IndexSource —20.7%Not comparable
AA-SciCodeSource —34.4%Not comparable
Reasoning
BenchmarkClaude Mythos 5GPT-OSS 20BResult
AA-LCRSource —30.7%Not comparable
CritPtSource —1.4%Not comparable
Knowledge
BenchmarkClaude Mythos 5GPT-OSS 20BResult
GPQASource 94.1%—Not comparable
HLESource 64.5%—Not comparable
HLE w/o toolsSource 59%—Not comparable
Artificial Analysis Intelligence IndexSource —14.9%Not comparable
AA-GPQA DiamondSource —68.8%Not comparable
AA-HLESource —9.8%Not comparable
AA-Omniscience IndexSource —-63.9%Not comparable
AA-Omniscience AccuracySource —15.5%Not comparable
AA-Omniscience Hallucination RateSource —94.1%Not comparable
Math
BenchmarkClaude Mythos 5GPT-OSS 20BResult
USAMO 2026Source 97.6%—Not comparable
Multilingual
BenchmarkClaude Mythos 5GPT-OSS 20BResult
SWE MultilingualSource 92.2%—Not comparable
Multimodal
BenchmarkClaude Mythos 5GPT-OSS 20BResult
SWE-bench MultimodalSource 54.9%—Not comparable
CharXivSource 93.5%—Not comparable
CharXiv w/o toolsSource 88.9%—Not comparable
Design Arena WebsiteSource —882Not comparable
Inst. Following
BenchmarkClaude Mythos 5GPT-OSS 20BResult
AA-IFBenchSource —65.1%Not comparable
Frequently Asked Questions (3)

Can I compare Claude Mythos 5 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 Mythos 5 and GPT-OSS 20B today?

Claude Mythos 5: $10.00 input / $50.00 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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