LLM Reference

Gemini 3.1 Pro Preview vs Phi-4 Mini Flash Reasoning

Gemini 3.1 Pro Preview (2026) and Phi-4 Mini Flash Reasoning (2025) are frontier reasoning models from Google DeepMind and Microsoft Research. Gemini 3.1 Pro Preview ships a 1m-token context window, while Phi-4 Mini Flash Reasoning ships a 128k-token context window. 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 fits 8x more tokens; pick it for long-context work and Phi-4 Mini Flash Reasoning for tighter calls.

Decision scorecard

Local evidence first
SignalGemini 3.1 Pro PreviewPhi-4 Mini Flash Reasoning
Best formultimodal apps, tool-calling agents, and long-context analysisreasoning-heavy apps
Decision fitCoding, RAG, and AgentsLong context
Context window1m128k
Cheapest output$12/1M tokens-
Provider routes5 tracked1 tracked
Shared benchmarks0 shared0 shared

Decision tradeoffs

Choose Gemini 3.1 Pro Preview when...
  • 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.
  • Gemini 3.1 Pro Preview uniquely exposes Vision, Multimodal, and JSON / Tool use in local model data.
  • Local decision data tags Gemini 3.1 Pro Preview for Coding, RAG, and Agents.
Choose Phi-4 Mini Flash Reasoning when...
  • Phi-4 Mini Flash Reasoning uniquely exposes Reasoning in local model data.
  • Local decision data tags Phi-4 Mini Flash Reasoning for Long context.

Monthly cost at traffic

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

Gemini 3.1 Pro Preview

$4,600

Cheapest tracked route/tier: Google AI Studio

Phi-4 Mini Flash Reasoning

Unavailable

No complete token price in local provider data

Cost delta unavailable until both models have sourced input and output token prices.

Switch friction

Gemini 3.1 Pro Preview -> Phi-4 Mini Flash Reasoning
  • No overlapping tracked provider route is sourced for Gemini 3.1 Pro Preview and Phi-4 Mini Flash Reasoning; plan for SDK, billing, or endpoint changes.
  • Check replacement coverage for Vision, Multimodal, and JSON / Tool use before moving production traffic.
  • Phi-4 Mini Flash Reasoning adds Reasoning in local capability data.
Phi-4 Mini Flash Reasoning -> Gemini 3.1 Pro Preview
  • No overlapping tracked provider route is sourced for Phi-4 Mini Flash Reasoning and Gemini 3.1 Pro Preview; plan for SDK, billing, or endpoint changes.
  • Check replacement coverage for Reasoning before moving production traffic.
  • Gemini 3.1 Pro Preview adds Vision, Multimodal, and JSON / Tool use in local capability data.

Specs

Specification
Released2026-02-192025-12-01
Context window1m128k
Parameters—3.8B
ArchitectureDecoder OnlyDecoder Only
LicenseProprietaryMITOSI-approved
OpennessProprietaryOpen source
WeightsNot releasedUnknown
CodeUnknownUnknown
Commercial useCommercial use: conditionalCommercial use: permitted
Knowledge cutoff2025-012025-02

Pricing and availability

Pricing attributeGemini 3.1 Pro PreviewPhi-4 Mini Flash Reasoning
Input price
0-200,001t
$2/1M tokens
200,001t+
$4/1M tokens
-
Output price
0-200,001t
$12/1M tokens
200,001t+
$18/1M tokens
-
Providers
Google AI StudioGCP Vertex AIOpenRouterReplicate APIVercel AI Gateway
NVIDIA NIM

Capabilities

CapabilityGemini 3.1 Pro PreviewPhi-4 Mini Flash Reasoning
VisionYesNo
MultimodalYesNo
ReasoningNoYes
JSON / Tool useYesNo
Structured outputsYesNo
Code executionYesNo
IDE integrationNoNo
Computer useNoNo
Parallel agentsNoNo

Benchmarks

No shared benchmark scores are currently available for this pair.

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Model pages
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Last reviewed: 2026-06-29. Data sourced from public model cards and provider documentation.