Gemini 3.5 Pro vs Phi-4 Mini Flash Reasoning
Gemini 3.5 Pro (2026) and Phi-4 Mini Flash Reasoning (2025) are frontier-tier reasoning models from Google DeepMind and Microsoft Research. Gemini 3.5 Pro ships a 2m-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 3.5 Pro fits 16x more tokens; pick it for long-context work and Phi-4 Mini Flash Reasoning for tighter calls.
Decision scorecard
Local evidence first| Signal | Gemini 3.5 Pro | Phi-4 Mini Flash Reasoning |
|---|---|---|
| Best for | reasoning-heavy apps, multimodal apps, and long-context analysis | reasoning-heavy apps |
| Decision fit | Long context and Vision | Long context |
| Context window | 2m | 128k |
| Cheapest output | - | - |
| Provider routes | 0 tracked | 1 tracked |
| Shared benchmarks | 0 shared | 0 shared |
Decision tradeoffs
- Gemini 3.5 Pro has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Gemini 3.5 Pro uniquely exposes Vision and Multimodal in local model data.
- Local decision data tags Gemini 3.5 Pro for Long context and Vision.
- Phi-4 Mini Flash Reasoning has broader tracked provider coverage for fallback and procurement flexibility.
- 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 3.5 Pro
Unavailable
No complete token price in local provider data
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
- No overlapping tracked provider route is sourced for Gemini 3.5 Pro and Phi-4 Mini Flash Reasoning; plan for SDK, billing, or endpoint changes.
- Check replacement coverage for Vision and Multimodal before moving production traffic.
- No overlapping tracked provider route is sourced for Phi-4 Mini Flash Reasoning and Gemini 3.5 Pro; plan for SDK, billing, or endpoint changes.
- Gemini 3.5 Pro adds Vision and Multimodal in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-05-19 | 2025-12-01 |
| Context window | 2m | 128k |
| Parameters | — | 3.8B |
| Architecture | - | Decoder Only |
| License | Proprietary | MITOSI-approved |
| Openness | Proprietary | Open source |
| Commercial use | Commercial use: conditional | Commercial use: permitted |
| Knowledge cutoff | - | 2025-02 |
Pricing and availability
| Pricing attribute | Gemini 3.5 Pro | Phi-4 Mini Flash Reasoning |
|---|---|---|
| Input price | - | - |
| Output price | - | - |
| Providers | - |
Pricing not yet sourced for either model.
Capabilities
| Capability | Gemini 3.5 Pro | Phi-4 Mini Flash Reasoning |
|---|---|---|
| Vision | Yes | No |
| Multimodal | Yes | No |
| Reasoning | Yes | Yes |
| Function calling | No | No |
| Tool use | No | No |
| Structured outputs | No | No |
| Code execution | No | No |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
No shared benchmark scores are currently available for this pair.
Deep dive
The capability footprint differs most on vision: Gemini 3.5 Pro and multimodal input: Gemini 3.5 Pro. Both models share reasoning mode, 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 3.5 Pro has no token price sourced yet and Phi-4 Mini Flash Reasoning has no token price sourced yet. Provider availability is 0 tracked routes versus 1. Treat unknown pricing as an integration gap, then verify the route you will actually call before estimating production spend.
Choose Gemini 3.5 Pro when long-context analysis and larger context windows are central to the workload. Choose Phi-4 Mini Flash Reasoning when provider fit and broader provider choice are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship. This keeps the decision grounded in measurable tradeoffs instead of brand-level assumptions. It also helps separate model capability from provider packaging, which can change cost and latency.
FAQ
Which has a larger context window, Gemini 3.5 Pro or Phi-4 Mini Flash Reasoning?
Gemini 3.5 Pro supports 2m tokens, while Phi-4 Mini Flash 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 3.5 Pro or Phi-4 Mini Flash Reasoning open source?
Gemini 3.5 Pro is listed under Proprietary. Phi-4 Mini Flash Reasoning is listed under MIT. 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 3.5 Pro or Phi-4 Mini Flash Reasoning?
Gemini 3.5 Pro 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 3.5 Pro or Phi-4 Mini Flash Reasoning?
Gemini 3.5 Pro 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 3.5 Pro or Phi-4 Mini Flash Reasoning?
Both Gemini 3.5 Pro and Phi-4 Mini Flash Reasoning expose reasoning mode. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Where can I run Gemini 3.5 Pro and Phi-4 Mini Flash Reasoning?
Gemini 3.5 Pro is available on the tracked providers still being sourced. Phi-4 Mini Flash Reasoning is available on NVIDIA NIM. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
Continue comparing
Last reviewed: 2026-06-20. Data sourced from public model cards and provider documentation.