Claude Sonnet 5 vs Claude Opus 4.8

Head-to-head technical comparison of intelligence, capabilities, and API pricing.

Claude Sonnet 5

Anthropic

AI Mastery Index94

LMSYS Arena1356

Technical (MMLU-Pro)94%

Cost per 1M Tokens$2

Claude Opus 4.8

Anthropic

AI Mastery Index94.6

LMSYS Arena1362

Technical (MMLU-Pro)94.5%

Cost per 1M Tokens$5

Architect's Verdict

When comparing Claude Sonnet 5 and Claude Opus 4.8, Claude Opus 4.8 edges out in overall capabilities according to the AI Mastery Index. However, for cost-sensitive workloads, Claude Sonnet 5 offers a more economical API at $2 per 1M tokens. Your choice should depend heavily on whether you prioritize raw reasoning (MMLU) or scalable deployment economics.