Magistral Medium 2509
Magistral Medium 2509 is Mistral AI's reasoning model for enterprise use, with 73.6% on AIME 2024 (single-sample), traceable chain-of-thought, and multilingual reasoning across eight languages.
import { streamText } from 'ai'
const result = streamText({ model: 'mistral/magistral-medium', prompt: 'Why is the sky blue?'})Playground
Try out Magistral Medium 2509 by Mistral AI. Usage is billed to your team at API rates. Free users (those who haven't made a payment) get $5 of credits every 30 days.
Providers
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P50 throughput on live AI Gateway traffic, in tokens per second (TPS). Visit the docs for more info.
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More models by Mistral AI
| Model |
|---|
| 256K | 0.3s | 69tps | $0.40/M | $2.00/M | — | — |  | 12/09/2025 | |||||
| 256K | 0.4s | 67tps | $0.50/M | $1.50/M | — | — | | 12/02/2025 | |||||
| 256K | 0.2s | 86tps | $0.20/M | $0.20/M | — | — | | 12/01/2025 | |||||
| 128K | 0.2s | 158tps | $0.10/M | $0.10/M | — | — | | 10/01/2024 | |||||
| 32K | 0.4s | $0.10/M | $0.30/M | — | — | | 09/01/2024 | ||||||
| $0.10/M | — | — | | 12/11/2023 |
About Magistral Medium 2509
Announced March 17, 2025, Magistral Medium 2509 is Mistral AI's first dedicated reasoning model and the more capable of the two Magistral variants. Magistral Medium 2509 scores 73.6% on AIME 2024, a standard mathematical reasoning benchmark, and reaches 90% with majority voting at 64 samples.
Magistral Medium 2509 produces traceable chain-of-thought (CoT) reasoning, exposing each inferential step rather than returning only a final answer. This transparency targets enterprise use cases in regulated industries like finance, legal, and healthcare.
Multilingual reasoning spans English, French, Spanish, German, Italian, Arabic, Russian, and Simplified Chinese. A single deployment can serve global teams without language-specific fallbacks.
What To Consider When Choosing a Provider
- Configuration: Magistral Medium 2509's transparent chain-of-thought output makes it particularly useful in regulated industries where auditability of AI reasoning steps is a compliance requirement.
- Zero Data Retention: AI Gateway supports Zero Data Retention for this model via direct gateway requests (BYOK is not included). To configure this, check the documentation.
- Authentication: AI Gateway authenticates requests using an API key or OIDC token. You do not need to manage provider credentials directly.
When to Use Magistral Medium 2509
Best For
- Mathematical reasoning: Quantitative problem solving requiring multi-step derivation
- Regulated industry applications: Finance, legal, and healthcare where reasoning auditability matters
- Business strategy analysis: Scenario modeling that benefits from structured thinking
- Multilingual reasoning workflows: Spanning European and Arabic-script languages
- Majority voting reliability: Applications where multiple reasoning passes improve answer reliability
Consider Alternatives When
- Cost-sensitive reasoning: Magistral Small's 70.7% AIME score meets your accuracy threshold
- Straightforward instruction following: Tasks that do not require extended reasoning
- Agentic code execution: You need code execution rather than reasoning (consider Devstral models)
Conclusion
Choose Magistral Medium 2509 when problem complexity justifies enterprise-tier capability. Magistral Medium 2509 delivers mathematical reasoning, transparent audit trails, and multilingual coverage across eight languages. Magistral Medium 2509 established Mistral AI's position in the reasoning model category.
Frequently Asked Questions
What is Magistral Medium 2509's AIME 2024 score?
73.6% single-sample, and 90% with majority voting at 64 samples.
What is traceable chain-of-thought reasoning?
Magistral Medium 2509 exposes each reasoning step rather than returning only a final answer. Users and auditors can follow the inferential process from question to conclusion.
Which languages does Magistral Medium 2509 support for reasoning?
English, French, Spanish, German, Italian, Arabic, Russian, and Simplified Chinese.
How does Magistral Medium 2509 differ from Magistral Small?
Magistral Medium 2509 is the larger variant. Magistral Small is a 24B open-source model under Apache 2.0 that scores 70.7% on AIME 2024. Choose Magistral Small when you prioritize lower cost over the extra 2.9 points on AIME 2024 single-sample.
Can Magistral Medium 2509 be used for software engineering tasks?
Yes. Software engineering is one of its listed domain expertise areas alongside business strategy and regulated industries.
Does Magistral Medium 2509 have a reasoning budget or thinking token parameter?
Mistral AI hasn't publicly disclosed configurable thinking budgets for Magistral Medium 2509.