Grok 3 vs Grok 4.1 Fast

Across our 12-test suite, neither model wins a majority. Wins/ties summary from our testing: Grok 3 wins safety calibration and agentic planning; Grok 4.1 Fast wins constrained rewriting and creative problem solving; the other eight tests tie. Detailed walk-through:

• safety calibration: Grok 3 = 2 vs Grok 4.1 Fast = 1. Grok 3 ranks 12 of 55 (20-model tie) vs Grok 4.1 Fast rank 32 of 55. Practical meaning: Grok 3 is likelier to refuse harmful prompts and better calibrated for safety-critical gating.
• agentic planning: Grok 3 = 5 (tied for 1st) vs Grok 4.1 Fast = 4 (rank 16). This indicates Grok 3 decomposes goals and plans recovery more robustly in our tests.
• constrained rewriting: Grok 3 = 3 (rank 31) vs Grok 4.1 Fast = 4 (rank 6). For tight character-limited compression tasks, Grok 4.1 Fast generated better-compressed, valid outputs.
• creative problem solving: Grok 3 = 3 (rank 30) vs Grok 4.1 Fast = 4 (rank 9). Grok 4.1 Fast produced more non-obvious, feasible ideas in our prompts.
• structured output: tie at 5; both tied for 1st (Grok 3 and Grok 4.1 Fast). Both reliably follow JSON/schema constraints in our tests.
• tool calling: tie at 4; both rank 18 of 54. Both select and sequence functions correctly at similar rates in our tool-calling tasks.
• faithfulness: tie at 5 (tied for 1st). Both stick to source material in our extraction and summarization tests.
• classification: tie at 4 (tied for 1st). Both route and categorize accurately in our scenarios.
• long context: tie at 5 (tied for 1st). Both score top marks on retrieval accuracy at 30K+ token prompts; Grok 4.1 Fast additionally provides a 2M context window in its model metadata, which matters for very large documents.
• persona consistency and multilingual: ties at 5 (both top-ranked). Both maintain persona and non-English quality in our samples.
• strategic analysis: tie at 5 (both top-ranked). Both produce nuanced tradeoff reasoning with numbers. Overall interpretation: functionally the models are closely matched across most core capabilities (structured output, faithfulness, long context, multilingual). Grok 3 pulls ahead when safety calibration and highest-ranked agentic planning are required; Grok 4.1 Fast pulls ahead for constrained rewriting and creative problem-solving and adds practical advantages: far lower cost and a 2M token window (plus uses_reasoning_tokens for reasoning-enabled flows).

Grok 3: input $3 / mTok, output $15 / mTok. Grok 4.1 Fast: input $0.2 / mTok, output $0.5 / mTok (priceRatio = 30 for output). Example monthly costs (input+output combined):

• 1M tokens (1,000 mTok): Grok 3 = $18,000 ($3,000 input + $15,000 output); Grok 4.1 Fast = $700 ($200 input + $500 output).
• 10M tokens (10,000 mTok): Grok 3 = $180,000; Grok 4.1 Fast = $7,000.
• 100M tokens (100,000 mTok): Grok 3 = $1,800,000; Grok 4.1 Fast = $70,000. Who should care: high-volume API users, startups, and cost-conscious teams will materially benefit from Grok 4.1 Fast’s lower rates and large context. Teams that must prioritize safety calibration or advanced agentic planning should weigh whether Grok 3’s higher cost is justified by its wins in those specific benchmarks.

Choose Grok 3 if: you need stronger safety calibration and the best agentic planning from our 12-test suite (scores: safety calibration 2 vs 1; agentic planning 5 vs 4) and you can absorb much higher per-token costs. Typical use cases: safety-sensitive automation, high-assurance decision workflows, or where the 5/5 agentic planning result is mission-critical. Choose Grok 4.1 Fast if: you want a production-ready, cost-efficient model that ties Grok 3 on most benchmarks, excels at constrained rewriting (4 vs 3) and creative problem solving (4 vs 3), and needs a very large (2M) context window. Typical use cases: high-volume chat and research agents, long-document retrieval, and budget-conscious deployments.