GPT-5.5 vs Phi-4 Reasoning Vision 15B
GPT-5.5 (2026) and Phi-4 Reasoning Vision 15B (2026) are frontier reasoning models from OpenAI and Microsoft Research. GPT-5.5 ships a 1.05m-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. It focuses on practical selection signals rather than broad model-family marketing.
GPT-5.5 is safer overall; choose Phi-4 Reasoning Vision 15B when vision-heavy evaluation matters.
Decision scorecard
Local evidence first| Signal | GPT-5.5 | Phi-4 Reasoning Vision 15B |
|---|---|---|
| Best for | reasoning-heavy apps, multimodal apps, and tool-calling agents | multimodal apps |
| Decision fit | Coding, RAG, and Agents | Vision |
| Context window | 1.05m | — |
| Cheapest output | $30/1M tokens | - |
| Provider routes | 4 tracked | 0 tracked |
| Shared benchmarks | 0 shared | 0 shared |
Decision tradeoffs
- GPT-5.5 has the larger context window for long prompts, retrieval packs, or transcript analysis.
- GPT-5.5 has broader tracked provider coverage for fallback and route flexibility.
- GPT-5.5 uniquely exposes Reasoning, JSON / Tool use, and Structured outputs in local model data.
- Local decision data tags GPT-5.5 for Coding, RAG, and Agents.
- 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.
GPT-5.5
$11,500
Cheapest tracked route/tier: OpenAI API 0-272K input tokens
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 GPT-5.5 and Phi-4 Reasoning Vision 15B; plan for SDK, billing, or endpoint changes.
- Check replacement coverage for Reasoning, JSON / Tool use, and Structured outputs before moving production traffic.
- No overlapping tracked provider route is sourced for Phi-4 Reasoning Vision 15B and GPT-5.5; plan for SDK, billing, or endpoint changes.
- GPT-5.5 adds Reasoning, JSON / Tool use, and Structured outputs in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-04-23 | 2026-03-12 |
| Context window | 1.05m | — |
| Parameters | — | 15B |
| Architecture | Decoder Only | - |
| License | Proprietary | MITOSI-approved |
| Openness | Proprietary | Open source |
| Weights | Not released | Unknown |
| Code | Unknown | Unknown |
| Commercial use | Commercial use: conditional | Commercial use: permitted |
| Knowledge cutoff | 2025-12 | 2025-03 |
Pricing and availability
| Pricing attribute | GPT-5.5 | Phi-4 Reasoning Vision 15B |
|---|---|---|
| Input price |
| - |
| Output price |
| - |
| Providers | - |
Capabilities
| Capability | GPT-5.5 | Phi-4 Reasoning Vision 15B |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | Yes | No |
| JSON / 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
No shared benchmark scores are currently available for this pair.
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Last reviewed: 2026-06-29. Data sourced from public model cards and provider documentation.