Gemini 3.1 Pro Preview vs Grok 3 Mini

Across our 12 internal benchmark tests, Gemini 3.1 Pro Preview wins 5, Grok 3 Mini wins 2, and the two tie on 5.

Where Gemini 3.1 Pro Preview wins:

• Strategic analysis (5 vs 3): Gemini 3.1 Pro Preview scores 5/5, tied for 1st among 54 models, while Grok 3 Mini scores 3/5, ranking 36th of 54. This measures nuanced tradeoff reasoning with real numbers — a meaningful gap for business analysis, decision support, and research tasks.
• Creative problem solving (5 vs 3): Gemini 3.1 Pro Preview scores 5/5 (tied for 1st among 54), Grok 3 Mini scores 3/5 (rank 30 of 54). This tests non-obvious, specific, feasible ideation — relevant for brainstorming, product design, and open-ended analysis.
• Agentic planning (5 vs 3): Gemini 3.1 Pro Preview scores 5/5 (tied for 1st among 54), Grok 3 Mini scores 3/5 (rank 42 of 54). This is a significant gap for developers building autonomous agents: goal decomposition and failure recovery are core to agentic reliability, and Grok 3 Mini sits in the bottom quartile here.
• Structured output (5 vs 4): Gemini 3.1 Pro Preview scores 5/5 (tied for 1st among 54), Grok 3 Mini scores 4/5 (rank 26 of 54). JSON schema compliance and format adherence matter for any API-integrated application — a one-point edge here is real.
• Multilingual (5 vs 4): Gemini 3.1 Pro Preview scores 5/5 (tied for 1st among 55), Grok 3 Mini scores 4/5 (rank 36 of 55). If your application serves non-English users, this difference is worth noting.

Where Grok 3 Mini wins:

• Tool calling (5 vs 4): Grok 3 Mini scores 5/5, tied for 1st among 54 models. Gemini 3.1 Pro Preview scores 4/5, ranking 18th of 54. This is function selection, argument accuracy, and sequencing — core to agentic and API-connected workflows. Notably, Grok 3 Mini's edge here partially offsets its weaker agentic planning score.
• Classification (4 vs 2): Grok 3 Mini scores 4/5 (tied for 1st among 53), while Gemini 3.1 Pro Preview scores just 2/5 (rank 51 of 53 — near the bottom). For routing, tagging, or content categorization workloads, Grok 3 Mini is the clear choice.

Ties (both models equal):

• Constrained rewriting (4/4): Both rank 6th of 53.
• Faithfulness (5/5): Both tied for 1st among 55 models — neither hallucinates on source material in our tests.
• Long context (5/5): Both tied for 1st among 55 models. Practically speaking, Gemini 3.1 Pro Preview's 1M+ token context window gives it a structural advantage for very long documents, even though both score identically at our tested retrieval depth.
• Safety calibration (2/2): Both rank 12th of 55, in the middle of the pack.
• Persona consistency (5/5): Both tied for 1st among 53 models.

External benchmark — AIME 2025 (Epoch AI): Gemini 3.1 Pro Preview scores 95.6% on AIME 2025, ranking 2nd of 23 models tested by Epoch AI. This places it among the strongest math reasoning models measured by that benchmark. Grok 3 Mini does not have an AIME 2025 score in the payload, so a direct comparison cannot be made. The AIME 2025 median across models with scores is 83.9%, making Gemini 3.1 Pro Preview's 95.6% notably above the midpoint.

The pricing gap between these two models is substantial. Gemini 3.1 Pro Preview costs $2.00 per million input tokens and $12.00 per million output tokens. Grok 3 Mini costs $0.30 per million input tokens and $0.50 per million output tokens. That's a 6.7x difference on input and a 24x difference on output.

In practice, this compounds quickly at scale. At 1M output tokens/month, Gemini 3.1 Pro Preview costs $12 versus Grok 3 Mini's $0.50 — a $11.50 difference that's easy to absorb. At 10M output tokens, that gap becomes $120 vs $5, or $115/month. At 100M output tokens — realistic for a production API serving thousands of users — you're looking at $1,200/month for Gemini 3.1 Pro Preview versus $50/month for Grok 3 Mini, a $1,150 monthly delta.

Who should care: Developers building high-throughput applications (chatbots, classification pipelines, bulk document processing) should weigh Grok 3 Mini seriously, especially given its strong tool calling score (5/5, tied for 1st among 54 models) and competitive classification performance. Teams running lower-volume but complex tasks — agentic systems, multimodal workflows, deep strategic analysis — will find Gemini 3.1 Pro Preview's benchmark advantages easier to justify. Gemini 3.1 Pro Preview also supports a 1,048,576-token context window versus Grok 3 Mini's 131,072 tokens, which can affect whether long-document tasks are even feasible on one model vs the other.

Choose Gemini 3.1 Pro Preview if:

• You're building agentic systems that require reliable goal decomposition and failure recovery (scored 5/5 vs Grok 3 Mini's 3/5 on agentic planning in our tests)
• Your application involves strategic analysis, complex reasoning, or nuanced tradeoff evaluation
• You need multimodal input — Gemini 3.1 Pro Preview supports text, image, file, audio, and video inputs; Grok 3 Mini is text-only
• You work with documents or contexts beyond 131K tokens (Gemini 3.1 Pro Preview's context window is 1,048,576 tokens)
• You need top-tier multilingual output quality
• Volume is low-to-moderate and the $12/M output token cost is acceptable for your use case
• Math reasoning quality matters — 95.6% on AIME 2025 (Epoch AI) is among the best in our dataset

Choose Grok 3 Mini if:

• You're running classification, routing, or tagging pipelines at scale — it scores 4/5 (tied for 1st) vs Gemini 3.1 Pro Preview's 2/5 (near last)
• Tool calling reliability is your primary concern — it scores 5/5, tied for 1st among 54 models
• You're processing high token volumes and cost is a constraint — $0.50/M output vs $12.00/M is a 24x savings
• Your inputs are text-only and you don't need long-context beyond 131K tokens
• You want access to raw reasoning traces (both models expose reasoning tokens, but Grok 3 Mini's description explicitly highlights this as a feature)
• Logic-based tasks without deep domain knowledge match your workload description