Claude Opus 4.5 vs Phi-3 Mini 4k
Claude Opus 4.5 (2025) and Phi-3 Mini 4k (2024) are frontier reasoning models from Anthropic and Microsoft Research. Claude Opus 4.5 ships a 200K-token context window, while Phi-3 Mini 4k ships a 4K-token context window. On MMLU PRO, Claude Opus 4.5 leads by 43.2 pts. On pricing, Phi-3 Mini 4k costs $0.05/1M input tokens versus $5/1M for the alternative. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit.
Phi-3 Mini 4k is ~9900% cheaper at $0.05/1M; pay for Claude Opus 4.5 only for coding workflow support.
Specs
| Released | 2025-11-01 | 2024-04-23 |
| Context window | 200K | 4K |
| Parameters | — | 3.8B |
| Architecture | decoder only | decoder only |
| License | Proprietary | Open Source |
| Knowledge cutoff | 2025-12 | - |
Pricing and availability
| Claude Opus 4.5 | Phi-3 Mini 4k | |
|---|---|---|
| Input price | $5/1M tokens | $0.05/1M tokens |
| Output price | $25/1M tokens | $0.25/1M tokens |
| Providers |
Capabilities
| Claude Opus 4.5 | Phi-3 Mini 4k | |
|---|---|---|
| Vision | ||
| Multimodal | ||
| Reasoning | ||
| Function calling | ||
| Tool use | ||
| Structured outputs | ||
| Code execution |
Benchmarks
| Benchmark | Claude Opus 4.5 | Phi-3 Mini 4k |
|---|---|---|
| MMLU PRO | 88.9 | 45.7 |
Deep dive
On shared benchmark coverage, MMLU PRO has Claude Opus 4.5 at 88.9 and Phi-3 Mini 4k at 45.7, with Claude Opus 4.5 ahead by 43.2 points. The largest visible gap is 43.2 points on MMLU PRO, which matters most when that benchmark mirrors your workload. Treat isolated benchmark wins as directional, because provider routing, prompt style, and tool access can move real application results.
The capability footprint differs most on vision: Claude Opus 4.5, multimodal input: Claude Opus 4.5, reasoning mode: Claude Opus 4.5, function calling: Claude Opus 4.5, tool use: Claude Opus 4.5, structured outputs: Claude Opus 4.5, and code execution: Claude Opus 4.5. Both models share the core language-model surface, 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.
For cost, Claude Opus 4.5 lists $5/1M input and $25/1M output tokens, while Phi-3 Mini 4k lists $0.05/1M input and $0.25/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Phi-3 Mini 4k lower by about $10.89 per million blended tokens. Availability is 6 providers versus 4, so concentration risk also matters.
Choose Claude Opus 4.5 when coding workflow support, larger context windows, and broader provider choice are central to the workload. Choose Phi-3 Mini 4k when provider fit and lower input-token cost are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship.
FAQ
Which has a larger context window, Claude Opus 4.5 or Phi-3 Mini 4k?
Claude Opus 4.5 supports 200K tokens, while Phi-3 Mini 4k supports 4K tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Which is cheaper, Claude Opus 4.5 or Phi-3 Mini 4k?
Phi-3 Mini 4k is cheaper on tracked token pricing. Claude Opus 4.5 costs $5/1M input and $25/1M output tokens. Phi-3 Mini 4k costs $0.05/1M input and $0.25/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Claude Opus 4.5 or Phi-3 Mini 4k open source?
Claude Opus 4.5 is listed under Proprietary. Phi-3 Mini 4k is listed under Open Source. 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, Claude Opus 4.5 or Phi-3 Mini 4k?
Claude Opus 4.5 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, Claude Opus 4.5 or Phi-3 Mini 4k?
Claude Opus 4.5 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.
Where can I run Claude Opus 4.5 and Phi-3 Mini 4k?
Claude Opus 4.5 is available on Microsoft Foundry, Anthropic, GCP Vertex AI, AWS Bedrock, and OpenRouter. Phi-3 Mini 4k is available on Microsoft Foundry, NVIDIA NIM, Baseten API, and Replicate API. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-04-24. Data sourced from public model cards and provider documentation.