Claude Opus 4.5 vs Phi-4 Mini Flash Reasoning
Claude Opus 4.5 (2025) and Phi-4 Mini Flash Reasoning (2025) are frontier-tier reasoning models from Anthropic and Microsoft Research. Claude Opus 4.5 ships a 200k-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. It focuses on practical selection signals rather than broad model-family marketing.
Phi-4 Mini Flash Reasoning is safer overall; choose Claude Opus 4.5 when coding workflow support matters.
Decision scorecard
Local evidence first| Signal | Claude Opus 4.5 | Phi-4 Mini Flash Reasoning |
|---|---|---|
| Best for | reasoning-heavy apps, multimodal apps, and tool-calling agents | reasoning-heavy apps |
| Decision fit | Coding, RAG, and Agents | Long context |
| Context window | 200k | 128k |
| Cheapest output | $25/1M tokens | - |
| Provider routes | 6 tracked | 1 tracked |
| Shared benchmarks | 0 shared | 0 shared |
Decision tradeoffs
- Claude Opus 4.5 has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Claude Opus 4.5 has broader tracked provider coverage for fallback and route flexibility.
- Claude Opus 4.5 uniquely exposes Vision, Multimodal, and JSON / Tool use in local model data.
- Local decision data tags Claude Opus 4.5 for Coding, RAG, and Agents.
- 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.
Claude Opus 4.5
$10,250
Cheapest tracked route/tier: Microsoft Foundry
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 Claude Opus 4.5 and Phi-4 Mini Flash Reasoning; plan for SDK, billing, or endpoint changes.
- Check replacement coverage for Vision, Multimodal, and JSON / Tool use before moving production traffic.
- No overlapping tracked provider route is sourced for Phi-4 Mini Flash Reasoning and Claude Opus 4.5; plan for SDK, billing, or endpoint changes.
- Claude Opus 4.5 adds Vision, Multimodal, and JSON / Tool use in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2025-11-01 | 2025-12-01 |
| Context window | 200k | 128k |
| Parameters | — | 3.8B |
| Architecture | Decoder Only | 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 | 2025-02 |
Pricing and availability
| Pricing attribute | Claude Opus 4.5 | Phi-4 Mini Flash Reasoning |
|---|---|---|
| Input price | $5/1M tokens | - |
| Output price | $25/1M tokens | - |
| Providers |
Capabilities
| Capability | Claude Opus 4.5 | Phi-4 Mini Flash Reasoning |
|---|---|---|
| Vision | Yes | No |
| Multimodal | Yes | No |
| Reasoning | Yes | Yes |
| 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: 2026-07-26. Data sourced from public model cards and provider documentation.