Claude Sonnet 5 vs GPT-5.6 Terra

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

Claude Sonnet 5

Anthropic

AI Mastery Index94.8

LMSYS Arena1472

Technical (MMLU-Pro)94.6%

Cost per 1M Tokens$2

GPT-5.6 Terra

OpenAI

AI Mastery Index93.9

LMSYS Arena1470

Technical (MMLU-Pro)93.5%

Cost per 1M Tokens$2.5

Architect's Verdict

When comparing Claude Sonnet 5 and GPT-5.6 Terra, Claude Sonnet 5 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.