Gemini 3.5 Pro vs Phi-4 Reasoning Vision 15B
Gemini 3.5 Pro (2026) and Phi-4 Reasoning Vision 15B (2026) are frontier reasoning models from Google DeepMind and Microsoft Research. Gemini 3.5 Pro ships a 2m-token context window, while Phi-4 Reasoning Vision 15B ships a not-yet-sourced 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 is safer overall; choose Phi-4 Reasoning Vision 15B when vision-heavy evaluation matters.
Decision scorecard
Local evidence first| Signal | Gemini 3.5 Pro | Phi-4 Reasoning Vision 15B |
|---|---|---|
| Best for | reasoning-heavy apps, multimodal apps, and long-context analysis | multimodal apps |
| Decision fit | Long context and Vision | Vision |
| Context window | 2m | — |
| 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 Reasoning in local model data.
- Local decision data tags Gemini 3.5 Pro for Long context and Vision.
- Local decision data tags Phi-4 Reasoning Vision 15B for Vision.
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 Reasoning Vision 15B
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 Reasoning Vision 15B; plan for SDK, billing, or endpoint changes.
- Check replacement coverage for Reasoning before moving production traffic.
- No overlapping tracked provider route is sourced for Phi-4 Reasoning Vision 15B and Gemini 3.5 Pro; plan for SDK, billing, or endpoint changes.
- Gemini 3.5 Pro adds Reasoning in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-05-19 | 2026-03-12 |
| Context window | 2m | — |
| Parameters | — | 15B |
| Architecture | - | - |
| License | Proprietary | MITOSI-approved |
| Openness | Proprietary | Open source |
| Commercial use | Commercial use: conditional | Commercial use: permitted |
| Knowledge cutoff | - | 2025-03 |
Pricing and availability
| Pricing attribute | Gemini 3.5 Pro | Phi-4 Reasoning Vision 15B |
|---|---|---|
| Input price | - | - |
| Output price | - | - |
| Providers | - | - |
Pricing not yet sourced for either model.
Capabilities
| Capability | Gemini 3.5 Pro | Phi-4 Reasoning Vision 15B |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | Yes | No |
| 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 reasoning mode: Gemini 3.5 Pro. Both models share vision and multimodal input, 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 Reasoning Vision 15B 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 reasoning depth are central to the workload. Choose Phi-4 Reasoning Vision 15B when vision-heavy evaluation 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
Is Gemini 3.5 Pro or Phi-4 Reasoning Vision 15B open source?
Gemini 3.5 Pro is listed under Proprietary. Phi-4 Reasoning Vision 15B 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 Reasoning Vision 15B?
Both Gemini 3.5 Pro and Phi-4 Reasoning Vision 15B expose vision. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Which is better for multimodal input, Gemini 3.5 Pro or Phi-4 Reasoning Vision 15B?
Both Gemini 3.5 Pro and Phi-4 Reasoning Vision 15B expose multimodal input. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Which is better for reasoning mode, Gemini 3.5 Pro or Phi-4 Reasoning Vision 15B?
Gemini 3.5 Pro 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.
When should I pick Gemini 3.5 Pro over Phi-4 Reasoning Vision 15B?
Gemini 3.5 Pro is safer overall; choose Phi-4 Reasoning Vision 15B when vision-heavy evaluation matters. If your workload also depends on reasoning depth, start with Gemini 3.5 Pro; if it depends on vision-heavy evaluation, run the same evaluation with Phi-4 Reasoning Vision 15B.
Continue comparing
Last reviewed: 2026-06-20. Data sourced from public model cards and provider documentation.