mistralai/Mistral-Small-4-119B-2603

Mistral Small 4 119B A6B

Mistral Small 4 is a powerful hybrid model capable of acting as both a general instruction model and a reasoning model. It unifies the capabilities of three different model families—Instruct, Reasoning (previously called Magistral), and Devstral—into a single, unified model.

With its multimodal capabilities, efficient architecture, and flexible mode switching, it is a powerful general-purpose model for any task. In a latency-optimized setup, Mistral Small 4 achieves a 40% reduction in end-to-end completion time, and in a throughput-optimized setup, it handles 3x more requests per second compared to Mistral Small 3.

To further improve efficiency you can either take advantages of:

• Speculative decoding thanks to our trained eagle head `mistralai/Mistral-Small-4-119B-2603-eagle`.
• 4 bit float precision quantization thanks to our NVFP4 checkpoint `mistralai/Mistral-Small-4-119B-2603-NVFP4`.

Key Features

Mistral Small 4 includes the following architectural choices:

• MoE: 128 experts, 4 active.
• 119B parameters, with 6.5B activated per token.
• 256k context length.
• Multimodal input: Accepts both text and image input, with text output.
• Instruct and Reasoning functionalities with function calls (reasoning effort configurable per request).

Mistral Small 4 offers the following capabilities:

• Reasoning Mode: Toggle between fast instant reply mode and reasoning mode, boosting performance with test-time compute when requested.
• Vision: Analyzes images and provides insights based on visual content, in addition to text.
• Multilingual: Supports dozens of languages, including English, French, Spanish, German, Italian, Portuguese, Dutch, Chinese, Japanese, Korean, and Arabic.
• System Prompt: Strong adherence and support for system prompts.
• Agentic: Best-in-class agentic capabilities with native function calling and JSON output.
• Speed-Optimized: Delivers best-in-class performance and speed.
• Apache 2.0 License: Open-source license for both commercial and non-commercial use.
• Large Context Window: Supports a 256k context window.

Recommended Settings

• Reasoning Effort:
• 'none' → Do not use reasoning
• 'high' → Use reasoning (recommended for complex prompts)

Use reasoning_effort="high" for complex tasks

• Temperature: 0.7 for reasoning_effort="high". Temp between 0.0 and 0.7 for reasoning_effort="none" depending on task.

Use Cases

Mistral Small 4 is designed for general chat assistants, coding, agentic tasks, and reasoning tasks (with reasoning mode toggled). Its multimodal capabilities also enable document and image understanding for data extraction and analysis.

Its capabilities are ideal for:

• Developers interested in coding and agentic capabilities for SWE automation and codebase exploration.
• Enterprises seeking general chat assistants, agents, and document understanding.
• Researchers leveraging its math and research capabilities.

Mistral Small 4 is also well-suited for customization and fine-tuning for more specialized tasks.

Examples

• General chat assistant
• Document parsing and extraction
• Coding agent
• Research assistant
• Customization & fine-tuning
• And more...

Benchmarks

Comparison with internal models

Depending on your tasks you can trigger reasoning thanks to the support of the per-request parameter reasoning_effort. Set it to:

• reasoning_effort="none": Fast, lightweight responses for everyday tasks, equivalent to the same chat style of `mistralai/Mistral-Small-3.2-24B-Instruct-2506`.
• reasoning_effort="high": Deep, step-by-step reasoning for complex problems, with equivalent verbosity to previous Magistral models such as `mistralai/Magistral-Small-2509`.

!Internal benchmark

Comparing Reasoning Models

!Internal benchmark - Reasoning

Comparison with other models

Mistral Small 4 with reasoning achieves competitive scores, matching or surpassing GPT-OSS 120B across all three benchmarks while generating significantly shorter outputs. On AA LCR, Mistral Small 4 scores 0.72 with just 1.6K characters, whereas Qwen models require 3.5-4x more output (5.8-6.1K) for comparable performance. On LiveCodeBench, Mistral Small 4 outperforms GPT-OSS 120B while producing 20% less output. This efficiency reduces latency, inference costs, and improves user experience.

!Comparison benchmark - LCR !Comparison benchmark - LiveCodeBench !Comparison benchmark - AIME25

Usage

You can find Mistral Small 4 support on multiple libraries for inference and fine-tuning. We here thank every contributors and maintainers that helped us making it happen.

Inference

The model can be deployed with:

• `vllm (recommended)`: See [here](#vllm-recommended)
• `llama.cpp`: See here for Unsloth's GGUFs
• `LM studio`: See here
• `SGLang`: See here
• `transformers`: See [here](#transformers)

For optimal performance, we recommend using the Mistral AI API if local serving is subpar.

Fine-Tuning

Fine-tune the model via:

• `Axolotl`: See here.

vLLM (Recommended)

We recommend using Mistral Small 4 with the vLLM library for production-ready inference.

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