Gemini 3.1 Flash-Lite vs Phi-4 Mini Reasoning
Gemini 3.1 Flash-Lite (2026) and Phi-4 Mini Reasoning (2026) are frontier reasoning models from Google DeepMind and Microsoft Research. Gemini 3.1 Flash-Lite ships a 1M-token context window, while Phi-4 Mini Reasoning ships a 128K-token context window. On Google-Proof Q&A, Gemini 3.1 Flash-Lite leads by 34.9 pts. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit. It focuses on practical selection signals rather than broad model-family marketing.
Gemini 3.1 Flash-Lite fits 8x more tokens; pick it for long-context work and Phi-4 Mini Reasoning for tighter calls.
Decision scorecard
Local evidence first| Signal | Gemini 3.1 Flash-Lite | Phi-4 Mini Reasoning |
|---|---|---|
| Best for | multimodal apps, tool-calling agents, and long-context analysis | reasoning-heavy apps |
| Decision fit | Coding, RAG, and Agents | Long context |
| Context window | 1M | 128K |
| Cheapest output | $1.50/1M tokens | - |
| Provider routes | 3 tracked | 0 tracked |
| Shared benchmarks | Google-Proof Q&A leader | 1 rows |
Decision tradeoffs
- Gemini 3.1 Flash-Lite leads the largest shared benchmark signal on Google-Proof Q&A by 34.9 points.
- Gemini 3.1 Flash-Lite has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Gemini 3.1 Flash-Lite has broader tracked provider coverage for fallback and procurement flexibility.
- Gemini 3.1 Flash-Lite uniquely exposes Vision, Multimodal, and Function calling in local model data.
- Local decision data tags Gemini 3.1 Flash-Lite for Coding, RAG, and Agents.
- Phi-4 Mini Reasoning uniquely exposes Reasoning in local model data.
- Local decision data tags Phi-4 Mini 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 Flash-Lite
$575
Cheapest tracked route/tier: Google AI Studio
Phi-4 Mini 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
- No overlapping tracked provider route is sourced for Gemini 3.1 Flash-Lite and Phi-4 Mini Reasoning; plan for SDK, billing, or endpoint changes.
- Check replacement coverage for Vision, Multimodal, and Function calling before moving production traffic.
- Phi-4 Mini Reasoning adds Reasoning in local capability data.
- No overlapping tracked provider route is sourced for Phi-4 Mini Reasoning and Gemini 3.1 Flash-Lite; plan for SDK, billing, or endpoint changes.
- Check replacement coverage for Reasoning before moving production traffic.
- Gemini 3.1 Flash-Lite adds Vision, Multimodal, and Function calling in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-05-07 | 2026-05-16 |
| Context window | 1M | 128K |
| Parameters | — | 3.8B |
| Architecture | decoder only | - |
| License | Proprietary | Proprietary |
| Knowledge cutoff | 2025-01 | 2025-02 |
Pricing and availability
| Pricing attribute | Gemini 3.1 Flash-Lite | Phi-4 Mini Reasoning |
|---|---|---|
| Input price | $0.25/1M tokens | - |
| Output price | $1.50/1M tokens | - |
| Providers | - |
Capabilities
| Capability | Gemini 3.1 Flash-Lite | Phi-4 Mini Reasoning |
|---|---|---|
| Vision | Yes | No |
| Multimodal | Yes | No |
| Reasoning | No | Yes |
| Function calling | Yes | No |
| Tool use | Yes | No |
| Structured outputs | Yes | No |
| Code execution | Yes | No |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
| Benchmark | Gemini 3.1 Flash-Lite | Phi-4 Mini Reasoning |
|---|---|---|
| Google-Proof Q&A | 86.9 | 52.0 |
Deep dive
On shared benchmark coverage, Google-Proof Q&A has Gemini 3.1 Flash-Lite at 86.9 and Phi-4 Mini Reasoning at 52, with Gemini 3.1 Flash-Lite ahead by 34.9 points. The largest visible gap is 34.9 points on Google-Proof Q&A, which matters most when that benchmark mirrors your workload. Treat isolated benchmark wins as directional, because provider routing, prompt style, and tool access can move real application results.
The capability footprint differs most on vision: Gemini 3.1 Flash-Lite, multimodal input: Gemini 3.1 Flash-Lite, reasoning mode: Phi-4 Mini Reasoning, function calling: Gemini 3.1 Flash-Lite, tool use: Gemini 3.1 Flash-Lite, structured outputs: Gemini 3.1 Flash-Lite, and code execution: Gemini 3.1 Flash-Lite. Both models share the core language-model surface, so the practical split is not just feature count. Use those differences to decide whether the page is about raw model quality, agentic coding support, multimodal ingestion, or predictable structured API behavior.
Pricing coverage is uneven: Gemini 3.1 Flash-Lite has $0.25/1M input tokens and Phi-4 Mini Reasoning has no token price sourced yet. Provider availability is 3 tracked routes versus 0. Treat unknown pricing as an integration gap, then verify the route you will actually call before estimating production spend.
Choose Gemini 3.1 Flash-Lite when coding workflow support, larger context windows, and broader provider choice are central to the workload. Choose Phi-4 Mini Reasoning when reasoning depth are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship.
FAQ
Which has a larger context window, Gemini 3.1 Flash-Lite or Phi-4 Mini Reasoning?
Gemini 3.1 Flash-Lite supports 1M tokens, while Phi-4 Mini Reasoning supports 128K tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Is Gemini 3.1 Flash-Lite or Phi-4 Mini Reasoning open source?
Gemini 3.1 Flash-Lite is listed under Proprietary. Phi-4 Mini Reasoning is listed under Proprietary. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for vision, Gemini 3.1 Flash-Lite or Phi-4 Mini Reasoning?
Gemini 3.1 Flash-Lite has the clearer documented vision signal in this comparison. If vision is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Which is better for multimodal input, Gemini 3.1 Flash-Lite or Phi-4 Mini Reasoning?
Gemini 3.1 Flash-Lite has the clearer documented multimodal input signal in this comparison. If multimodal input is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Which is better for reasoning mode, Gemini 3.1 Flash-Lite or Phi-4 Mini Reasoning?
Phi-4 Mini Reasoning has the clearer documented reasoning mode signal in this comparison. If reasoning mode is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Where can I run Gemini 3.1 Flash-Lite and Phi-4 Mini Reasoning?
Gemini 3.1 Flash-Lite is available on Google AI Studio, OpenRouter, and Vercel AI Gateway. Phi-4 Mini Reasoning is available on the tracked providers still being sourced. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-05-22. Data sourced from public model cards and provider documentation.