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Claude Mythos 5.1 vs Claude Opus 5

4 SHARED BENCHMARKS

Across 4 shared benchmarks, Claude Mythos 5.1 scores higher on 2 and Claude Opus 5 on 2. The widest gap is BioMysteryBench (Human Difficult), where Claude Opus 5 scores 51.8 against 44.1.

ANTHROPICVSANTHROPIC4 SHARED2–2 HEAD-TO-HEAD

BenchmarkClaude Mythos 5.1MARGINClaude Opus 5

BioMysteryBench (Human Difficult)44.151.8

BioMysteryBench (Human Solvable)90.391.4

ProteinGym Hard49.347.7

Terminal-Bench 4.060.952

Best tracked score per model per benchmark (default configuration; source-attributed). ↓ marks lower-is-better metrics. Open either model for its full surface, provenance and pricing.

Compare Claude Opus 5 withEVERY TRACKED PAIRING

▶Anthropic11 PAIRINGS

Claude Opus 4.8 Claude Opus 4.6 Claude Sonnet 4.5 Claude 3.5 Sonnet Claude Opus 4.5 Claude Fable 5 Claude Opus 4.7 Claude Sonnet 4 Claude Sonnet 4.6 Claude Sonnet 5 Claude Opus 4

▶OpenAI11 PAIRINGS

GPT-5.5 GPT-4o GPT-5.6 Sol GPT-5.2 GPT-5.4 GPT-5 o3 GPT-5.1 o4-mini o1 GPT-4o mini

▶Google11 PAIRINGS

Gemini 3.1 Pro Gemini 3 Pro Gemma 4 26B A4B Gemini 1.5 Pro Gemma 4 31B Gemini 2.5 Pro Gemini 3.5 Flash Gemini 3 Flash Preview Gemini 3.6 Flash Gemma 4 E2B Gemini 2.5 Flash

▶Alibaba11 PAIRINGS

Qwen3.5 35B A3B Qwen3.5 397B A17B Qwen3 VL 4B (Reasoning)Qwen2.5 Instruct 72B Qwen3.5 27B Qwen3.6 Plus Qwen3.6 27B Qwen3.6 35B A3B Qwen3.7 Max Qwen3.5 122B A10B Qwen3.7 Plus Preview

▶DeepSeek5 PAIRINGS

DeepSeek-V3 DeepSeek-V4-Pro DeepSeek-V3.2 DeepSeek-V4-Flash DeepSeek-R1

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Kimi K2.5 Kimi K2.6 Kimi K3 Kimi K2 Instruct

▶Meta2 PAIRINGS

Llama 3.1 Instruct 405B Muse Spark 1.1

▶Z.ai2 PAIRINGS

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▶MiniMax1 PAIRING

▶NVIDIA1 PAIRING

Nemotron 3 Super 120B A12B