Gemini 3.1 Pro Preview vs Grok 4.1 Fast

Summary of head-to-heads (our 12-test suite):

• Gemini wins (A): creative_problem_solving 5 vs 4 — Gemini’s 5 (ranked tied for 1st) indicates stronger non-obvious, feasible idea generation for product/design exploration. safety_calibration 2 vs 1 — Gemini refuses harmful requests more accurately in our tests (A rank 12 of 55 vs B rank 32 of 55). agentic_planning 5 vs 4 — Gemini scores top-tier on goal decomposition and failure recovery (A tied for 1st; Grok rank 16).
• Grok wins (B): classification 4 vs 2 — Grok is far better at routing/categorization in our tests (Grok tied for 1st; Gemini ranks 51 of 53). This matters for support triage, intent routing, and automated tagging.
• Ties (both models equal): structured_output 5/5, strategic_analysis 5/5, constrained_rewriting 4/4, tool_calling 4/4, faithfulness 5/5, long_context 5/5, persona_consistency 5/5, multilingual 5/5. Practical meaning: both models reliably adhere to JSON/schema outputs, handle nuanced tradeoff reasoning, preserve source fidelity, and keep persona/translation quality high in our testing. Additional context and differentiators from the payload: Gemini posts an external AIME 2025 score of 95.6% (Epoch AI) and ranks 2 of 23 on that external math benchmark — a strong signal for high-difficulty reasoning (attributed to Epoch AI). Tool calling is tied at 4/5 for both and both models share the same tool_calling rank (18 of 54, with many ties), so neither has a clear edge on basic function-selection correctness in our suite. Note context windows: Gemini has a 1,048,576 token window; Grok’s window is 2,000,000 tokens — Grok’s larger context window can be a practical advantage for very long documents despite both scoring 5 on long_context in our tests.

Costs in the payload are per 1k tokens (mtok). Combined input+output cost per 1k tokens: Gemini = $2 + $12 = $14.00; Grok = $0.20 + $0.50 = $0.70. At 1M tokens/month (1,000 mtok) that’s Gemini $14,000 vs Grok $700. At 10M tokens (10,000 mtok): Gemini $140,000 vs Grok $7,000. At 100M tokens (100,000 mtok): Gemini $1,400,000 vs Grok $70,000. The payload’s priceRatio is 24x. Conclusion: teams with low to moderate volume or tight budgets should prefer Grok 4.1 Fast; organizations doing research, high-value agentic workflows, or who can justify steep per-token spend may choose Gemini 3.1 Pro Preview despite the large cost gap.

Choose Gemini 3.1 Pro Preview if: you need top-tier creative problem solving, agentic planning, and stronger safety calibration in our tests (Gemini wins those 3 benchmarks), you value the AIME 2025 result (95.6% on AIME 2025, Epoch AI, rank 2/23), and you can absorb high per-token costs. Choose Grok 4.1 Fast if: you must minimize inference cost (Grok combined $0.70 per 1k tokens vs Gemini $14), need best-in-test classification/routing (Grok wins classification and ties for 1st), or require the largest possible context window (2,000,000 tokens) for long-document or transcript workloads.