GPT-4.1 vs Grok 4.1 Fast

Full comparison across our 12-test suite (scores from payload). Ties (8/12): strategic analysis (5 vs 5), faithfulness (5 vs 5), classification (4 vs 4), long context (5 vs 5), safety calibration (1 vs 1), persona consistency (5 vs 5), agentic planning (4 vs 4) and multilingual (5 vs 5) — these ties mean both models are equivalent for nuanced reasoning, retrieval at 30K+ tokens, multilingual output, basic routing/classification, and safety calibration in our tests. GPT-4.1 wins: tool calling 5 vs 4 (GPT-4.1 tied for 1st with 16 others out of 54; Grok ranks 18/54) — this translates to more reliable function selection, argument accuracy and sequencing for complex agent flows. GPT-4.1 also wins constrained rewriting 5 vs 4 (tied for 1st in our ranking), which matters when you need strict compression or exact-format rewrites. Grok 4.1 Fast wins structured output 5 vs 4 (tied for 1st with 24 others) — better JSON/schema compliance — and creative problem solving 4 vs 3 (rank 9/54 vs GPT-4.1’s rank 30/54), which shows Grok generates more non-obvious, feasible ideas in our tests. External benchmarks (supplementary): GPT-4.1 scores 48.5% on SWE-bench Verified, 83% on MATH Level 5, and 38.3% on AIME 2025 (Epoch AI); Grok 4.1 Fast has no external scores in the payload. In short: GPT-4.1 is measurably stronger where precise tool orchestration and tight-format rewrites matter; Grok 4.1 Fast is stronger for schema fidelity and ideation, while being dramatically cheaper.

Pricing per 1,000 tokens (mTok) from the payload: GPT-4.1 input $2 + output $8 = $10/mTok; Grok 4.1 Fast input $0.2 + output $0.5 = $0.70/mTok. Assuming a 1:1 input:output token split, monthly costs are: 1M tokens (1,000 mTok) → GPT-4.1 $10,000 vs Grok $700; 10M tokens → GPT-4.1 $100,000 vs Grok $7,000; 100M tokens → GPT-4.1 $1,000,000 vs Grok $70,000. The output-cost ratio (8 vs 0.5) is 16x, matching the payload priceRatio; at scale this gap dominates infrastructure cost. Teams building large-scale chatbots, search augmentation, or high-throughput APIs should care deeply about Grok’s lower per-token bill; teams where marginal quality on tool orchestration or constrained rewriting reduces engineering overhead may justify GPT-4.1’s higher cost.

Choose GPT-4.1 if you need the best tool-calling and constrained-rewriting behavior in production agentic systems (GPT-4.1: tool calling 5/5, constrained rewriting 5/5) and you can absorb higher runtime costs. Choose Grok 4.1 Fast if you need cheaper at-scale inference (combined $0.70/mTok vs $10/mTok for GPT-4.1), superior structured-output compliance (5/5), or better creative-problem solving (4/5) for customer support, research, or high-throughput generative tasks.