Gemini 3 Flash Preview vs Grok Code Fast 1

Gemini 3 Flash Preview wins 9 of 12 benchmarks in our testing, ties 2, and loses 1. Here's the breakdown:

Where Flash Preview wins clearly:

• Tool calling: 5 vs 4 (tied for 1st among 54 models vs rank 18 of 54). This gap matters in agentic workflows where function selection accuracy and argument sequencing determine whether a pipeline runs or fails.
• Structured output: 5 vs 4 (tied for 1st among 54 vs rank 26 of 54). For API integrations dependent on JSON schema compliance, Flash Preview is significantly more reliable.
• Strategic analysis: 5 vs 3 (tied for 1st among 54 vs rank 36 of 54). A two-point gap on nuanced tradeoff reasoning is substantial — Grok Code Fast 1 sits in the bottom third of tested models here.
• Creative problem solving: 5 vs 3 (tied for 1st among 54, alongside only 7 other models, vs rank 30 of 54). Flash Preview is in rare company at this score; Grok Code Fast 1 is below the field median.
• Faithfulness: 5 vs 4 (tied for 1st among 55 vs rank 34 of 55). Sticking to source material without hallucinating is critical for RAG and summarization tasks — Flash Preview has a clear edge.
• Long context: 5 vs 4 (tied for 1st among 55 vs rank 38 of 55). Grok Code Fast 1 also has a 256K context ceiling vs Flash Preview's 1M tokens, compounding the score difference for long-document work.
• Persona consistency: 5 vs 4 (tied for 1st among 53 vs rank 38 of 53). Relevant for chatbot and assistant deployments.
• Multilingual: 5 vs 4 (tied for 1st among 55 vs rank 36 of 55). Flash Preview handles non-English output at top-tier quality; Grok Code Fast 1 falls into the lower quarter of tested models.
• Constrained rewriting: 4 vs 3 (rank 6 of 53 vs rank 31 of 53). Compressing text within hard character limits — Flash Preview is well above the median; Grok Code Fast 1 is below it.

Where they tie:

• Classification: both score 4, both tied for 1st with 29 other models among 53 tested. No meaningful difference.
• Agentic planning: both score 5, both tied for 1st with 14 other models among 54 tested. Goal decomposition and failure recovery are equally strong.

Where Grok Code Fast 1 wins:

• Safety calibration: 2 vs 1 (rank 12 of 55 vs rank 32 of 55). Grok Code Fast 1 does a better job refusing harmful requests while permitting legitimate ones. Flash Preview's score of 1 is in the bottom tier across all 55 tested models — a meaningful limitation for consumer-facing deployments.

External benchmarks (Epoch AI): Flash Preview scores 75.4% on SWE-bench Verified, ranking 3rd of 12 models with external scores — placing it among the strongest coding models by that third-party measure. It also scores 92.8% on AIME 2025 (rank 5 of 23), indicating strong mathematical reasoning. Grok Code Fast 1 has no external benchmark scores in the payload for direct comparison on these dimensions.

Gemini 3 Flash Preview costs $0.50/MTok input and $3.00/MTok output. Grok Code Fast 1 costs $0.20/MTok input and $1.50/MTok output — 2.5× cheaper on output, which is typically the dominant cost driver. At 1M output tokens/month, Flash Preview costs $3.00 vs $1.50 for Grok Code Fast 1 — a $1.50/month difference that barely registers. At 10M output tokens/month the gap widens to $15, still manageable for most teams. At 100M output tokens/month — a serious production scale — Flash Preview costs $300 vs $150, a $150/month difference that starts to matter for margin-sensitive applications. Grok Code Fast 1 also has a smaller context window (256K tokens vs Flash Preview's 1M tokens), which limits its usefulness on long-document workloads regardless of price. Developers running high-volume, short-context agentic coding pipelines are the clearest audience for Grok Code Fast 1's cost advantage. Anyone needing long-context retrieval, multilingual output, or broad reasoning capability will find Flash Preview's premium hard to argue against.

Choose Gemini 3 Flash Preview if: you need a model that handles the full range of tasks — agentic workflows with reliable tool calling, long-document retrieval (up to 1M tokens), multilingual output, strategic analysis, or creative work. It also supports text, image, file, audio, and video inputs, giving it flexibility Grok Code Fast 1 lacks. Its 75.4% SWE-bench Verified score (Epoch AI) makes it competitive for coding tasks too. The $3.00/MTok output cost is the price of that breadth.

Choose Grok Code Fast 1 if: your workload is narrowly focused on agentic coding, your context needs fit within 256K tokens, volume is high enough that the $1.50/MTok output rate materially affects your costs, and you want visible reasoning traces to debug or steer model behavior. Its safety calibration score (2 vs Flash Preview's 1) also makes it a better fit for applications where over-refusal is a lower risk than under-refusal. Outside of those specific conditions, Flash Preview's benchmark lead is too wide to ignore.