Mistral Medium 3.5 (Reasoning)
by Mistral AI
Mistral Medium 3.5 (Reasoning) is a reasoning model from Mistral AI, released on April 29, 2026. It has a 256K-token context window and can generate up to 256K output tokens. API pricing is $1.5 per 1M input tokens and $7.5 per 1M output tokens. It ranks #93 of 220 models by Intelligence Score with a score of 26.7.
Mistral Medium 3.5 is Mistral AI's first flagship merged model: a dense 128B-parameter multimodal model with a 256k context window that unifies instruction-following, reasoning, and coding capabilities in a single set of weights. It replaces Mistral Medium 3.1 and Magistral in Le Chat, and Devstral 2 in the Vibe coding agent. Reasoning effort is configurable per request, and the vision encoder was trained from scratch to handle variable image sizes and aspect ratios. Released as open weights under a Modified MIT License.
Key specs
| Provider | Mistral AI |
|---|---|
| Release date | 2026-04-29 |
| License | open weights |
| Context window | 256K tokens |
| Max output | 256K tokens |
| Input price | $1.5 / 1M tokens |
| Output price | $7.5 / 1M tokens |
| Intelligence Score | 26.7 |
| Coding index | 23.5 |
| Output speed | 378 tokens/s |
| Time to first token | 14.26 s |
Quick answers
What is the context window of Mistral Medium 3.5 (Reasoning)?
Mistral Medium 3.5 (Reasoning) has a context window of 256K tokens, with a maximum output of 256K tokens per response.
How much does Mistral Medium 3.5 (Reasoning) cost?
Mistral Medium 3.5 (Reasoning) costs $1.5 per 1M input tokens and $7.5 per 1M output tokens through the API.
Is Mistral Medium 3.5 (Reasoning) open source?
Yes. Mistral Medium 3.5 (Reasoning) is an open model released under the open weights license.
When was Mistral Medium 3.5 (Reasoning) released?
Mistral AI released Mistral Medium 3.5 (Reasoning) on April 29, 2026.
How does Mistral Medium 3.5 (Reasoning) compare to Claude Opus 5.5 (Reasoning)?
Mistral Medium 3.5 (Reasoning) scores 26.7 on the Intelligence Score versus 60.5 for Claude Opus 5.5 (Reasoning), the current #1. Input pricing is $1.5 vs $4 per 1M tokens.
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