Overview
Mistral Medium 3.1 (API id mistral-medium-2508, version 25.08) is Mistral AI's frontier-class multimodal model, released on August 12, 2025. It is an incremental refresh of Mistral Medium 3 that adds improvements in reasoning, coding, STEM, and tone control while keeping the same cost and deployment profile. The model accepts text and image input and returns text, with a 128K-token context window.
Mistral positions the Medium line under the banner 'Medium is the new large': it claims Medium 3 performs at or above 90% of Claude Sonnet 3.7 on benchmarks across the board, surpasses leading open models such as Llama 4 Maverick, and does so at roughly 8x lower cost. Pricing is $0.40 per million input tokens and $2.00 per million output tokens. Unlike the later Mistral Medium 3.5, Medium 3.1 is proprietary and is not released as open weights, though Mistral offers hybrid, on-premises, and in-VPC deployment for enterprise customers (four GPUs and above).
Mistral Medium 3.1 is available through Mistral's La Plateforme API as well as third-party gateways such as OpenRouter and the Vercel AI Gateway. It has since been deprecated (scheduled deprecation 2026-05-22, retirement 2026-08-31) in favor of Mistral Medium 3.5, the open-weight successor. Mistral has not published a detailed per-benchmark (MMLU/GPQA/HumanEval) breakdown for this version, so this page reports only the specifications the company and major model trackers have verified.
| Released | 2025-08-12 |
|---|---|
| License | Proprietary (commercial API; enterprise self-hosted/in-VPC deployment available) |
| Weights | API only |
| Context | 128K |
| Architecture | Mistral's proprietary multimodal Medium-class model (text + image input, text output). Released as an incremental update over Mistral Medium 3 with improvements in reasoning, coding, STEM, tone, and instruction-following. Designed for simple deployment, including self-hosted environments of four GPUs and above. Exact parameter count and architecture details are not publicly disclosed by Mistral AI. |
| Modalities | Text, Vision |
| Status | Deprecated (retiring 2026-08-31; succeeded by Mistral Medium 3.5) |
Pricing
| Input | $0.40 / 1M tokens per 1M tokens |
|---|---|
| Output | $2.00 / 1M tokens per 1M tokens |
Pricing announced for the Mistral Medium 3 line and consistently reported for Medium 3.1 by Artificial Analysis, OpenRouter, and the Vercel AI Gateway.
Strengths
- Strong coding and STEM performance for its price tier, a focus area Mistral highlights for the Medium line
- Cost-efficient: $0.40 input / $2.00 output per 1M tokens, roughly 8x cheaper than the frontier models Mistral benchmarks it against
- Multimodal: handles both text and image (vision) input
- 128K-token context window for long documents and codebases
- Flexible deployment, including hybrid, on-premises, in-VPC, and self-hosted on four GPUs and above for enterprises
- Improved tone, reasoning, and instruction-following over the original Mistral Medium 3
Best for
- Coding assistance and code generation
- STEM reasoning and technical question answering
- Enterprise workflows requiring on-premises or in-VPC deployment
- Document and image understanding (vision input)
- Cost-sensitive production applications that need frontier-class quality at a mid-tier price
- Multilingual chat and content generation
How to access
| Provider | Model ID |
|---|---|
| Mistral AI (La Plateforme) ↗ | mistral-medium-2508 |
| OpenRouter ↗ | mistralai/mistral-medium-3.1 |
| Vercel AI Gateway ↗ | mistral/mistral-medium |
Mistral Medium — every version
The full lineage of the Mistral Medium line, newest first. Every version has its own page — click any to compare specs, benchmarks and pricing.
| Version | Released | Context | License |
|---|---|---|---|
| Mistral Medium 3.5current | 2026-04-28 | — | MIT |
| Mistral Medium 3.1 | 2025-08-12 | — | Open weights |
| Mistral Medium 3 | 2025-05-07 | — | Open weights |
| Mistral Medium (2023) | 2023-12 | — | Proprietary |
FAQ
When was Mistral Medium 3.1 released?
Mistral AI released Mistral Medium 3.1 on August 12, 2025. Its API identifier is mistral-medium-2508 (version 25.08).
Is Mistral Medium 3.1 open weights?
No. Mistral Medium 3.1 is proprietary and available via API; its weights were not publicly released. The later Mistral Medium 3.5 is the open-weight successor in this line. Enterprises can, however, run Medium 3.1 through hybrid, on-premises, or in-VPC deployments arranged with Mistral.
How much does Mistral Medium 3.1 cost?
It is priced at $0.40 per million input tokens and $2.00 per million output tokens, the same pricing Mistral announced for the Medium 3 line and roughly 8x cheaper than the frontier models Mistral compares it against.
What is the context window and what modalities does it support?
Mistral Medium 3.1 has a 128K-token context window. It is multimodal, accepting both text and image (vision) input and producing text output.