Gemini 2.5 Pro vs Grok 4.1 Fast

Summary of our 12-test comparison (scores are from our testing unless noted):

• Gemini wins (in our tests): creative_problem_solving 5 vs 4 (Gemini ranks tied for 1st with 7 others; Grok ranks 9 of 54). Tool_calling 5 vs 4 (Gemini tied for 1st with 16 others; Grok rank 18 of 54). Practical effect: Gemini is likelier to select the right function, order calls correctly, and produce non-obvious feasible ideas.
• Grok wins (in our tests): strategic_analysis 5 vs 4 (Grok tied for 1st with 25 others; Gemini rank 27 of 54). constrained_rewriting 4 vs 3 (Grok rank 6 of 53; Gemini rank 31 of 53). Practical effect: Grok is stronger at nuanced tradeoff reasoning and hitting tight character/format constraints.
• Ties (equivalent scores in our tests): structured_output 5/5 (both tied for 1st), faithfulness 5/5 (both tied for 1st), classification 4/4 (both tied for 1st), long_context 5/5 (both tied for 1st), safety_calibration 1/1 (both weak on refusals), persona_consistency 5/5, agentic_planning 4/4, multilingual 5/5. Practical effect: you should expect similar performance for schema compliance, factual sticking to source, long-context retrieval (30K+ tokens), multilingual output, and maintaining persona across both models.
• External benchmarks: Beyond our internal tests, Gemini scores 57.6% on SWE-bench Verified (Epoch AI) and 84.2% on AIME 2025 (Epoch AI). Grok has no external scores in the payload. These external results supplement our verdict: Gemini shows strong math ability on AIME but middling SWE-bench performance.
• Safety: both models score 1 on safety_calibration in our tests (rank 32 of 55), so neither is a reliable safety gate without additional guardrails. In short: Gemini edges ahead on function-selection and creative-solution tasks; Grok leads at strategic reasoning and tight-format rewriting; on many practical dimensions they tie.

Pricing (payload): Gemini 2.5 Pro input $1.25/1k tokens, output $10/1k tokens. Grok 4.1 Fast input $0.20/1k, output $0.50/1k. Assuming a 50/50 split of input/output tokens: at 1M tokens/month (1,000 mTok) Gemini ≈ $11,250/month (input $1,250 + output $10,000) vs Grok ≈ $700/month (input $200 + output $500). At 10M tokens/month Gemini ≈ $112,500 vs Grok ≈ $7,000. At 100M tokens/month Gemini ≈ $1,125,000 vs Grok ≈ $70,000. Who should care: startups, SaaS products, and high-volume APIs will see massive savings with Grok; research teams or teams needing Gemini’s specific strengths should budget for the much higher cost (output alone is $10/1k). The payload’s priceRatio (20) reflects that output token costs dominate the gap.

Choose Gemini 2.5 Pro if: you need best-in-class tool calling and creative problem solving, large multimodal context with Gemini’s supported modalities, or higher-end math performance (AIME 2025 84.2% in Epoch AI’s tests). Expect to pay substantially more per token. Choose Grok 4.1 Fast if: you’re building high-volume products or customer-facing agents and need cost-effective scale (Grok costs ~$700 vs $11,250/month at 1M tokens under a 50/50 I/O split), or you prioritize strategic analysis and constrained rewriting (Grok wins those benchmarks). If you need both sets of strengths, consider hybrid usage: route heavy, cheap inference to Grok and critical tool-calling or creative tasks to Gemini.