o3 Mini vs Phi-3 Mini 4k
o3 Mini (2025) and Phi-3 Mini 4k (2024) are frontier reasoning models from OpenAI and Microsoft Research. o3 Mini ships a not-yet-sourced context window, while Phi-3 Mini 4k ships a 4K-token context window. On MMLU PRO, o3 Mini leads by 33.4 pts. On pricing, Phi-3 Mini 4k costs $0.05/1M input tokens versus $1.1/1M for the alternative. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit.
Phi-3 Mini 4k is ~2100% cheaper at $0.05/1M; pay for o3 Mini only for coding workflow support.
Specs
| Released | 2025-03-31 | 2024-04-23 |
| Context window | — | 4K |
| Parameters | — | 3.8B |
| Architecture | decoder only | decoder only |
| License | Unknown | Open Source |
| Knowledge cutoff | 2025-04 | - |
Pricing and availability
| o3 Mini | Phi-3 Mini 4k | |
|---|---|---|
| Input price | $1.1/1M tokens | $0.05/1M tokens |
| Output price | $4.4/1M tokens | $0.25/1M tokens |
| Providers |
Capabilities
| o3 Mini | Phi-3 Mini 4k | |
|---|---|---|
| Vision | ||
| Multimodal | ||
| Reasoning | ||
| Function calling | ||
| Tool use | ||
| Structured outputs | ||
| Code execution |
Benchmarks
| Benchmark | o3 Mini | Phi-3 Mini 4k |
|---|---|---|
| MMLU PRO | 79.1 | 45.7 |
| Google-Proof Q&A | 79.7 | 40.9 |
Deep dive
On shared benchmark coverage, MMLU PRO has o3 Mini at 79.1 and Phi-3 Mini 4k at 45.7, with o3 Mini ahead by 33.4 points; Google-Proof Q&A has o3 Mini at 79.7 and Phi-3 Mini 4k at 40.9, with o3 Mini ahead by 38.8 points. The largest visible gap is 38.8 points on Google-Proof Q&A, 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 reasoning mode: o3 Mini, function calling: o3 Mini, tool use: o3 Mini, structured outputs: o3 Mini, and code execution: o3 Mini. 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, o3 Mini lists $1.1/1M input and $4.4/1M 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 $1.98 per million blended tokens. Availability is 3 providers versus 4, so concentration risk also matters.
Choose o3 Mini when coding workflow support are central to the workload. Choose Phi-3 Mini 4k when provider fit, lower input-token cost, and broader provider choice are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship.
FAQ
Which is cheaper, o3 Mini or Phi-3 Mini 4k?
Phi-3 Mini 4k is cheaper on tracked token pricing. o3 Mini costs $1.1/1M input and $4.4/1M 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 o3 Mini or Phi-3 Mini 4k open source?
o3 Mini is listed under Unknown. 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 reasoning mode, o3 Mini or Phi-3 Mini 4k?
o3 Mini 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.
Which is better for function calling, o3 Mini or Phi-3 Mini 4k?
o3 Mini has the clearer documented function calling signal in this comparison. If function calling is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Which is better for tool use, o3 Mini or Phi-3 Mini 4k?
o3 Mini has the clearer documented tool use signal in this comparison. If tool use is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Where can I run o3 Mini and Phi-3 Mini 4k?
o3 Mini is available on OpenRouter, OpenAI Batch API, and Azure OpenAI. 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.