Grok 4.1 Fast vs o4 Mini

In our 12-test suite the pair ties on 10 tasks, splits the remaining two, and shows clear trade-offs: - Ties (both 5/5 unless noted): structured output (5/5; tied for 1st), strategic analysis (5/5; tied for 1st), creative problem solving (4/4; rank 9 of 54 tied), faithfulness (5/5; tied for 1st), classification (4/4; tied for 1st), long context (5/5; tied for 1st), safety calibration (1/1; rank 32 of 55 tied), persona consistency (5/5; tied for 1st), agentic planning (4/4; rank 16 of 54 tied), multilingual (5/5; tied for 1st). These ties mean both models are equivalent for JSON schema adherence, strategic reasoning, long-context retrieval, persona, multilingual output, faithfulness, and classification in our tests. - Grok 4.1 Fast wins constrained rewriting (Grok 4 vs o4 3). Grok ranks 6 of 53 here versus o4 at rank 31; this indicates Grok better meets hard character/format compression constraints in our rewriting tests. - o4 Mini wins tool calling (o4 5 vs Grok 4); o4 Mini is tied for 1st on tool calling (tied with 16 models) while Grok ranks 18 of 54. That maps to more accurate function selection, argument construction, and sequencing in our tool-calling scenarios. - External math benchmarks (supplementary): o4 Mini scores 97.8% on MATH Level 5 and 81.7% on AIME 2025 (Epoch AI). We surface these Epoch AI results as supportive evidence that o4 Mini is stronger on competitive/structured math tasks. Practical meaning: choose o4 Mini for workflows where tool calling correctness and top-tier math performance materially change outcomes; choose Grok where cost, enormous context (2,000,000-token window), and constrained rewriting are priorities.

Per the payload, Grok 4.1 Fast costs $0.20 (input) / $0.50 (output) per mTok; o4 Mini costs $1.10 / $4.40 per mTok. Assuming 1 mTok = 1,000 tokens and a 50/50 input:output split, combined cost per mTok is $0.70 for Grok vs $5.50 for o4 Mini. At 1M tokens/month (1,000 mTok) that’s ~$700 (Grok) vs ~$5,500 (o4 Mini). At 10M tokens/month it’s ~$7,000 vs ~$55,000; at 100M tokens/month it’s ~$70,000 vs ~$550,000. Teams with high-volume inference, cheap embedding-heavy workflows, or tight budgets should care deeply about this gap; teams prioritizing marginal gains in tool selection or specific math/problem-solving benchmarks may justify o4 Mini’s higher cost.

Choose Grok 4.1 Fast if you need massive context windows (2,000,000 tokens), constrained-rewriting fidelity, or far lower cost for high-volume deployment — it costs $0.20/$0.50 per mTok and won our constrained rewriting test. Choose o4 Mini if you need the best tool calling behavior and top math/problem-solving performance (o4 Mini wins tool calling and scores 97.8% on MATH Level 5, 81.7% on AIME 2025 per Epoch AI) and you can absorb the higher cost ($1.10/$4.40 per mTok).