Gemini 3.1 Pro Preview vs Grok 4.20

Summary of our 12-test suite (scores shown are our 1-5 proxies unless otherwise noted). Wins and ties are reported from our testing. Gemini 3.1 Pro Preview (A) wins: creative_problem_solving 5 vs 4 (Gemini ranks tied 1st of 54; Grok ranks 9th of 54) — meaning Gemini produces more non-obvious, feasible ideas in our prompts. Safety_calibration 2 vs 1 (Gemini rank 12 of 55; Grok rank 32 of 55) — Gemini is more likely in our tests to refuse harmful requests while permitting legitimate ones. Agentic_planning 5 vs 4 (Gemini tied for 1st; Grok rank 16) — Gemini better decomposes goals and failure recovery in our scenarios. Grok 4.20 (B) wins: tool_calling 5 vs 4 (Grok tied for 1st of 54; Gemini rank 18) — in our tool-calling tests Grok selects functions, arguments, and sequencing more reliably. Classification 4 vs 2 (Grok tied for 1st; Gemini rank 51 of 53) — Grok outperformed Gemini on routing/labeling tasks in our tests. Ties (no clear winner in our testing): structured_output 5/5 (both tied for 1st), strategic_analysis 5/5 (both tied for 1st), constrained_rewriting 4/4 (both rank 6/53), faithfulness 5/5 (both tied for 1st), long_context 5/5 (both tied for 1st), persona_consistency 5/5 (both tied for 1st), multilingual 5/5 (both tied for 1st). Practical meaning: Gemini is the better pick when you need higher creative output, better planning and slightly stronger safety calibration. Grok is the better pick when you need reliable tool integration and classification at half the output price. Additional external result: Gemini scores 95.6% on AIME 2025 (Epoch AI) in our data and is ranked 2 of 23 on that test — a strong signal for advanced math reasoning in our testing.

Gemini and Grok share the same input price ($2 per 1k tokens); Gemini charges $12/1k output tokens while Grok charges $6/1k (price ratio 2x). At 1,000,000 tokens (1M) total: output-only cost = $12,000 (Gemini) vs $6,000 (Grok); including input at same volume (both $2/1k) total = $14,000 (Gemini) vs $8,000 (Grok). At 10M tokens total = $140,000 (Gemini) vs $80,000 (Grok). At 100M tokens = $1,400,000 (Gemini) vs $800,000 (Grok). The cost gap matters for high-volume generation (chatbots, long-document summarization, batch content production) — teams with heavy output budgets should prefer Grok for cost-efficiency; teams prioritizing top-tier planning/creative accuracy may accept Gemini’s premium.

Choose Gemini 3.1 Pro Preview if you need top-tier creative problem solving, agentic planning, stronger safety calibration, or peak math performance (AIME 2025: 95.6% in our data) and can absorb a higher output price ($12/1k). Choose Grok 4.20 if you need best-in-class tool calling and classification, a larger context window (2,000,000 tokens), or are cost-sensitive — Grok’s $6/1k output halves generation costs at scale while matching Gemini on structured output, long context, faithfulness, and multilingual performance.