Mistral Magistral Small 2509 vs Phi-4 Mini Flash Reasoning
Mistral Magistral Small 2509 (2025) and Phi-4 Mini Flash Reasoning (2025) are frontier reasoning models from MistralAI and Microsoft Research. Mistral Magistral Small 2509 ships a not-yet-sourced 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.
Phi-4 Mini Flash Reasoning is safer overall; choose Mistral Magistral Small 2509 when provider fit matters.
Decision scorecard
Local evidence first| Signal | Mistral Magistral Small 2509 | Phi-4 Mini Flash Reasoning |
|---|---|---|
| Best for | provider-routed production | reasoning-heavy apps |
| Decision fit | General | Long context |
| Context window | — | 128k |
| Cheapest output | $1.50/1M tokens | - |
| Provider routes | 2 tracked | 1 tracked |
| Shared benchmarks | 0 rows | 0 rows |
Decision tradeoffs
- Mistral Magistral Small 2509 has broader tracked provider coverage for fallback and procurement flexibility.
- Phi-4 Mini Flash Reasoning has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Phi-4 Mini Flash Reasoning uniquely exposes Reasoning in local model data.
- 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.
Mistral Magistral Small 2509
$775
Cheapest tracked route/tier: AWS Bedrock
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 Mistral Magistral Small 2509 and Phi-4 Mini Flash Reasoning; plan for SDK, billing, or endpoint changes.
- Phi-4 Mini Flash Reasoning adds Reasoning in local capability data.
- No overlapping tracked provider route is sourced for Phi-4 Mini Flash Reasoning and Mistral Magistral Small 2509; plan for SDK, billing, or endpoint changes.
- Check replacement coverage for Reasoning before moving production traffic.
Specs
| Specification | ||
|---|---|---|
| Released | 2025-09-01 | 2025-12-01 |
| Context window | — | 128k |
| Parameters | 24B | 3.8B |
| Architecture | - | decoder only |
| License | Apache 2.0(OSI) | MIT(OSI) |
| Openness | Open source | Open source |
| Commercial use | Commercial use allowed | Commercial use allowed |
| Knowledge cutoff | - | 2025-02 |
Pricing and availability
| Pricing attribute | Mistral Magistral Small 2509 | Phi-4 Mini Flash Reasoning |
|---|---|---|
| Input price | $0.50/1M tokens | - |
| Output price | $1.50/1M tokens | - |
| Providers |
Capabilities
| Capability | Mistral Magistral Small 2509 | Phi-4 Mini Flash Reasoning |
|---|---|---|
| Vision | No | No |
| Multimodal | No | No |
| Reasoning | No | Yes |
| 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 rows are currently sourced for this pair.
Deep dive
The capability footprint differs most on reasoning mode: Phi-4 Mini Flash Reasoning. 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.
Pricing coverage is uneven: Mistral Magistral Small 2509 has $0.50/1M input tokens and Phi-4 Mini Flash Reasoning has no token price sourced yet. Provider availability is 2 tracked routes versus 1. Treat unknown pricing as an integration gap, then verify the route you will actually call before estimating production spend.
Choose Mistral Magistral Small 2509 when provider fit and broader provider choice are central to the workload. Choose Phi-4 Mini Flash Reasoning when reasoning depth 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 Mistral Magistral Small 2509 or Phi-4 Mini Flash Reasoning open source?
Mistral Magistral Small 2509 is listed under Apache 2.0. Phi-4 Mini Flash Reasoning 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 reasoning mode, Mistral Magistral Small 2509 or Phi-4 Mini Flash Reasoning?
Phi-4 Mini Flash Reasoning 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.
Where can I run Mistral Magistral Small 2509 and Phi-4 Mini Flash Reasoning?
Mistral Magistral Small 2509 is available on AWS Bedrock and Vercel AI Gateway. Phi-4 Mini Flash Reasoning is available on NVIDIA NIM. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
When should I pick Mistral Magistral Small 2509 over Phi-4 Mini Flash Reasoning?
Phi-4 Mini Flash Reasoning is safer overall; choose Mistral Magistral Small 2509 when provider fit matters. If your workload also depends on provider fit, start with Mistral Magistral Small 2509; if it depends on reasoning depth, run the same evaluation with Phi-4 Mini Flash Reasoning.
Continue comparing
Last reviewed: 2026-05-22. Data sourced from public model cards and provider documentation.