Gemini 3.5 Pro vs Phi-4 Mini Reasoning
Gemini 3.5 Pro (2026) and Phi-4 Mini Reasoning (2026) 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 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. It focuses on practical selection signals rather than broad model-family marketing.
Gemini 3.5 Pro fits 16x more tokens; pick it for long-context work and Phi-4 Mini Reasoning for tighter calls.
Decision scorecard
Local evidence first| Signal | Gemini 3.5 Pro | Phi-4 Mini 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 | 0 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.
- 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 3.5 Pro
Unavailable
No complete token price in local provider data
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 3.5 Pro and Phi-4 Mini 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 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 | 2026-05-16 |
| Context window | 2m | 128k |
| Parameters | — | 3.8B |
| Architecture | - | - |
| 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 Reasoning |
|---|---|---|
| Input price | - | - |
| Output price | - | - |
| Providers | - | - |
Pricing not yet sourced for either model.
Capabilities
| Capability | Gemini 3.5 Pro | Phi-4 Mini 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 Reasoning has no token price sourced yet. Provider availability is 0 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 3.5 Pro when long-context analysis and larger context windows are central to the workload. Choose Phi-4 Mini Reasoning when provider fit 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. For teams standardizing a stack, that distinction is often the difference between a benchmark win and a reliable deployment.
FAQ
Which has a larger context window, Gemini 3.5 Pro or Phi-4 Mini Reasoning?
Gemini 3.5 Pro supports 2m 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 3.5 Pro or Phi-4 Mini Reasoning open source?
Gemini 3.5 Pro is listed under Proprietary. Phi-4 Mini 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 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 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 Reasoning?
Both Gemini 3.5 Pro and Phi-4 Mini Reasoning expose reasoning mode. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
When should I pick Gemini 3.5 Pro over Phi-4 Mini Reasoning?
Gemini 3.5 Pro fits 16x more tokens; pick it for long-context work and Phi-4 Mini Reasoning for tighter calls. If your workload also depends on long-context analysis, start with Gemini 3.5 Pro; if it depends on provider fit, run the same evaluation with Phi-4 Mini Reasoning.
Continue comparing
Last reviewed: 2026-06-20. Data sourced from public model cards and provider documentation.