Gemini 3.1 Pro Preview vs Grok 4

Gemini 3.1 Pro Preview (2026) and Grok 4 (2025) are frontier reasoning models from Google DeepMind and xAI. Gemini 3.1 Pro Preview ships a 1m-token context window, while Grok 4 ships a 256k-token context window. On MMLU PRO, Gemini 3.1 Pro Preview leads by 4.0 pts. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.

Gemini 3.1 Pro Preview is safer overall; choose Grok 4 when coding workflow support matters.

Decision scorecard

Local evidence first
SignalGemini 3.1 Pro PreviewGrok 4
Best formultimodal apps, tool-calling agents, and long-context analysisreasoning-heavy apps, multimodal apps, and tool-calling agents
Decision fitCoding, RAG, and AgentsCoding, RAG, and Agents
Context window1m256k
Cheapest output$12/1M tokens$2.50/1M tokens
Provider routes5 tracked4 tracked
Shared benchmarksMMLU PRO leader8 shared

Decision tradeoffs

Choose Gemini 3.1 Pro Preview when...
  • Gemini 3.1 Pro Preview holds a shared-benchmark lead on MMLU PRO, ahead by 4.0 points.
  • Gemini 3.1 Pro Preview has the larger context window for long prompts, retrieval packs, or transcript analysis.
  • Gemini 3.1 Pro Preview has broader tracked provider coverage for fallback and route flexibility.
  • Local decision data tags Gemini 3.1 Pro Preview for Coding, RAG, and Agents.
Choose Grok 4 when...
  • Grok 4 holds a shared-benchmark lead on τ-bench, ahead by 2.4 points.
  • Grok 4 has the lower cheapest tracked output price at $2.50/1M tokens.
  • Grok 4 uniquely exposes Reasoning in local model data.
  • Local decision data tags Grok 4 for Coding, RAG, and Agents.

Monthly cost at traffic

Estimate token spend from the cheapest tracked input and output route or tier on this page.

Lower estimate Grok 4

Gemini 3.1 Pro Preview

$4,600

Cheapest tracked route/tier: Google AI Studio

Grok 4

$1,625

Cheapest tracked route/tier: xAI Console

Estimated monthly gap: $2,975. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.

Switch friction

Gemini 3.1 Pro Preview -> Grok 4
  • Provider overlap exists on OpenRouter and Replicate API; start route-level A/B tests there.
  • Grok 4 is $9.50/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
  • Grok 4 adds Reasoning in local capability data.
Grok 4 -> Gemini 3.1 Pro Preview
  • Provider overlap exists on OpenRouter and Replicate API; start route-level A/B tests there.
  • Gemini 3.1 Pro Preview is $9.50/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
  • Check replacement coverage for Reasoning before moving production traffic.

Specs

Specification
Released2026-02-192025-07-09
Context window1m256k
Parameters——
ArchitectureDecoder OnlyDecoder Only
LicenseProprietaryProprietary
OpennessProprietaryProprietary
WeightsNot releasedNot released
CodeUnknownUnknown
Commercial useCommercial use: conditionalCommercial use: conditional
Knowledge cutoff2025-01-

Pricing and availability

Pricing attributeGemini 3.1 Pro PreviewGrok 4
Input price
0-200,001t
$2/1M tokens
200,001t+
$4/1M tokens
$1.25/1M tokens
Output price
0-200,001t
$12/1M tokens
200,001t+
$18/1M tokens
$2.50/1M tokens
Providers
Google AI StudioGCP Vertex AIOpenRouterReplicate APIVercel AI Gateway
Microsoft FoundryOpenRouterReplicate APIxAI Console

Capabilities

CapabilityGemini 3.1 Pro PreviewGrok 4
VisionYesYes
MultimodalYesYes
ReasoningNoYes
JSON / Tool useYesYes
Structured outputsYesYes
Code executionYesYes
IDE integrationNoNo
Computer useNoNo
Parallel agentsNoNo

Benchmarks

BenchmarkGemini 3.1 Pro PreviewGrok 4
MMLU PRO91.087.0
SWE-bench Verified80.676.7
Google-Proof Q&A94.387.5
AIME 202595.091.7
LiveCodeBench91.779.0
Humanity's Last Exam51.425.4
ARC-AGI-277.115.9
τ-bench76.578.9

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Last reviewed: 2026-07-10. Data sourced from public model cards and provider documentation.