Grok 4.5 vs Gemini 3.1 Ultra

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

Grok 4.5

xAI

AI Mastery Index93.4

LMSYS Arena1465

Technical (MMLU-Pro)92.8%

Cost per 1M Tokens$2

Gemini 3.1 Ultra

Google

AI Mastery Index92.5

LMSYS Arena1480

Technical (MMLU-Pro)92.5%

Cost per 1M Tokens$20

Architect's Verdict

When comparing Grok 4.5 and Gemini 3.1 Ultra, Grok 4.5 edges out in overall capabilities according to the AI Mastery Index. However, for cost-sensitive workloads, Grok 4.5 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.