Mistral Magistral Small 2509 vs Mistral Medium 3.5
Mistral Magistral Small 2509 (2025) and Mistral Medium 3.5 (2026) are frontier reasoning models from MistralAI. Mistral Magistral Small 2509 ships a not-yet-sourced context window, while Mistral Medium 3.5 ships a 256K-token context window. On pricing, Mistral Magistral Small 2509 costs $0.5/1M input tokens versus $1.5/1M for the alternative. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit.
Mistral Magistral Small 2509 is ~200% cheaper at $0.5/1M; pay for Mistral Medium 3.5 only for reasoning depth.
Specs
| Specification | ||
|---|---|---|
| Released | 2025-09-01 | 2026-04-29 |
| Context window | — | 256K |
| Parameters | — | 128B |
| Architecture | - | decoder only |
| License | Proprietary | Mistral License |
| Knowledge cutoff | - | - |
Pricing and availability
| Pricing attribute | Mistral Magistral Small 2509 | Mistral Medium 3.5 |
|---|---|---|
| Input price | $0.5/1M tokens | $1.5/1M tokens |
| Output price | $1.5/1M tokens | $7.5/1M tokens |
| Providers |
Capabilities
| Capability | Mistral Magistral Small 2509 | Mistral Medium 3.5 |
|---|---|---|
| Vision | No | Yes |
| Multimodal | No | Yes |
| Reasoning | No | Yes |
| Function calling | No | Yes |
| Tool use | No | Yes |
| Structured outputs | No | Yes |
| Code execution | No | No |
Benchmarks
No shared benchmark rows are currently sourced for this pair.
Deep dive
The capability footprint differs most on vision: Mistral Medium 3.5, multimodal input: Mistral Medium 3.5, reasoning mode: Mistral Medium 3.5, function calling: Mistral Medium 3.5, tool use: Mistral Medium 3.5, and structured outputs: Mistral Medium 3.5. 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, Mistral Magistral Small 2509 lists $0.5/1M input and $1.5/1M output tokens, while Mistral Medium 3.5 lists $1.5/1M input and $7.5/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Mistral Magistral Small 2509 lower by about $2.5 per million blended tokens. Availability is 1 providers versus 1, so concentration risk also matters.
Choose Mistral Magistral Small 2509 when provider fit and lower input-token cost are central to the workload. Choose Mistral Medium 3.5 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.
FAQ
Which is cheaper, Mistral Magistral Small 2509 or Mistral Medium 3.5?
Mistral Magistral Small 2509 is cheaper on tracked token pricing. Mistral Magistral Small 2509 costs $0.5/1M input and $1.5/1M output tokens. Mistral Medium 3.5 costs $1.5/1M input and $7.5/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Mistral Magistral Small 2509 or Mistral Medium 3.5 open source?
Mistral Magistral Small 2509 is listed under Proprietary. Mistral Medium 3.5 is listed under Mistral License. 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, Mistral Magistral Small 2509 or Mistral Medium 3.5?
Mistral Medium 3.5 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, Mistral Magistral Small 2509 or Mistral Medium 3.5?
Mistral Medium 3.5 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.
Which is better for reasoning mode, Mistral Magistral Small 2509 or Mistral Medium 3.5?
Mistral Medium 3.5 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 Mistral Medium 3.5?
Mistral Magistral Small 2509 is available on AWS Bedrock. Mistral Medium 3.5 is available on Mistral AI Studio. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
Continue comparing
Last reviewed: 2026-05-11. Data sourced from public model cards and provider documentation.