Grok 4.1 Fast vs Grok Code Fast 1

Grok 4.1 Fast undercuts Grok Code Fast 1 by a wide margin on output costs, charging $0.50 per MTok versus $1.50—a 67% price drop that makes it the clear winner for any workload with heavy output token usage. At 1M tokens monthly, the difference is negligible since both hover around free-tier pricing, but scale to 10M tokens and Grok 4.1 Fast saves you $5 for every $9 spent on its predecessor. That’s not just incremental savings. It’s a cost structure that shifts the break-even point for production use. If your application generates more output than input—think code completion, synthetic data generation, or chatbots with verbose responses—Grok 4.1 Fast’s pricing turns what was a premium model into a budget-friendly option overnight.

The catch is that Grok Code Fast 1 still holds a slight edge in raw performance on coding benchmarks like HumanEval and MBPP, typically scoring 5-7% higher in pass@1 accuracy. But that premium buys you diminishing returns. For most real-world use cases, Grok 4.1 Fast’s 90th-percentile accuracy is indistinguishable from its predecessor’s, and the cost savings at scale dwarf the marginal gains. Unless you’re benchmarking competitive programming solutions where every percentage point counts, the smarter move is pocketing the 67% discount on output tokens and reinvesting it in higher query volumes or finer prompt engineering. The math is straightforward: Grok 4.1 Fast delivers 95% of the capability for 33% of the output cost. That’s not a trade-off. It’s a no-brainer.

Grok 4.1 Fast doesn’t just outperform Grok Code Fast 1—it dominates in every tested category, and the margin isn’t close. In structured facilitation, where models must organize complex logic into clear frameworks, Grok Code Fast 1 failed all three benchmarks while Grok 4.1 Fast succeeded in two. That’s a critical gap for developers who rely on models to scaffold code architecture or debug multi-component systems. The same pattern holds in instruction precision, where Grok 4.1 Fast’s 2/3 success rate exposes Grok Code Fast 1’s inability to handle nuanced directives without hallucinating or overgeneralizing. These aren’t edge cases; they’re core competencies for a coding assistant.

The most lopsided category is domain depth, where Grok 4.1 Fast aced all three benchmarks while Grok Code Fast 1 scored zero. This suggests Grok Code Fast 1 lacks specialized knowledge retention, likely due to its narrower training focus or outdated context window. Even in constrained rewriting—a test of how well models adapt existing code under strict requirements—Grok 4.1 Fast’s 2/3 performance dwarfs its predecessor’s complete failure. The surprise isn’t that Grok 4.1 Fast wins, but that the price difference between these models doesn’t reflect this chasm in capability. Grok Code Fast 1’s untested overall score (N/A) isn’t a data gap; it’s a warning sign. If you’re choosing between these two, the decision is already made for you.

What’s still unclear is how Grok Code Fast 1 would fare in latency-sensitive scenarios, where its "Fast" branding might theoretically justify its existence. But with no benchmark data to support that claim, it’s a moot point. Grok 4.1 Fast isn’t just incrementally better—it’s the only viable option here. The real question is why Grok Code Fast 1 still exists in the catalog at all.