Model Comparison
Mistral Medium 3.5 vs GPT-5.5 InstantWhich is better in 2026?
Mistral Medium 3.5 significantly outperforms across most benchmarks. Mistral Medium 3.5 is 3.8x cheaper per token.
Verdict: Mistral Medium 3.5 vs GPT-5.5 Instant — which is better?
Mistral Medium 3.5 (by Mistral AI) and GPT-5.5 Instant (by OpenAI) are two of the AI models people compare most. Here is how they stack up on benchmarks, price and capabilities, and which one to pick in 2026.
Mistral Medium 3.5 outperforms in 1 benchmarks (AIME 2025), while GPT-5.5 Instant is better at 0 benchmarks. Mistral Medium 3.5 significantly outperforms across most benchmarks.
On price, Mistral Medium 3.5 is roughly 3.8x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
GPT-5.5 Instant also accepts a larger context window (400,000 input tokens), making it the stronger choice for long documents and large codebases.
Choose Mistral Medium 3.5 if…
- you want the strongest raw capability — it leads on 1 of 1 shared benchmarks
- cost matters — it's about 3.8x cheaper per token
- you need open weights you can self-host or fine-tune
Choose GPT-5.5 Instant if…
- you process long inputs — it offers a 400,000 token context window
- you want the most recent training data — it shipped May 2026
Performance Benchmarks
Comparative analysis across standard metrics
Mistral Medium 3.5 outperforms in 1 benchmarks (AIME 2025), while GPT-5.5 Instant is better at 0 benchmarks.
Mistral Medium 3.5 significantly outperforms across most benchmarks.
Arena Performance
Human preference votes
Pricing Analysis
Price comparison per million tokens
For input processing, Mistral Medium 3.5 ($1.50/1M tokens) is 3.3x cheaper than GPT-5.5 Instant ($5.00/1M tokens).
For output processing, Mistral Medium 3.5 ($7.50/1M tokens) is 4.0x cheaper than GPT-5.5 Instant ($30.00/1M tokens).
In conclusion, GPT-5.5 Instant is more expensive than Mistral Medium 3.5.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
GPT-5.5 Instant accepts 400,000 input tokens compared to Mistral Medium 3.5's 256,000 tokens. Mistral Medium 3.5 can generate longer responses up to 256,000 tokens, while GPT-5.5 Instant is limited to 128,000 tokens.
Input Capabilities
Supported data types and modalities
Both Mistral Medium 3.5 and GPT-5.5 Instant support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
Mistral Medium 3.5
GPT-5.5 Instant
License
Usage and distribution terms
Mistral Medium 3.5 is licensed under Modified MIT License, while GPT-5.5 Instant uses a proprietary license.
License differences may affect how you can use these models in commercial or open-source projects.
Modified MIT License
Open weights
Proprietary
Closed source
Release Timeline
When each model was launched
Mistral Medium 3.5 was released on 2026-04-29, while GPT-5.5 Instant was released on 2026-05-05.
GPT-5.5 Instant is 0 month newer than Mistral Medium 3.5.
Apr 29, 2026
2 months ago
May 5, 2026
2 months ago
6d newerKnowledge Cutoff
When training data ends
GPT-5.5 Instant has a documented knowledge cutoff of 2025-08-31, while Mistral Medium 3.5's cutoff date is not specified.
We can confirm GPT-5.5 Instant's training data extends to 2025-08-31, but cannot make a direct comparison without Mistral Medium 3.5's cutoff date.
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Aug 2025
Provider Availability
Mistral Medium 3.5 is available from Mistral AI. GPT-5.5 Instant is available from OpenAI.
Mistral Medium 3.5
GPT-5.5 Instant
Outputs Comparison
Key Takeaways
Mistral Medium 3.5
View detailsMistral AI
Detailed Comparison
Interactive Arena
Judge for yourself.
Run your own prompts against Mistral Medium 3.5 and GPT-5.5 Instant side-by-side, then vote on the output you prefer.
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FAQ
Common questions about Mistral Medium 3.5 vs GPT-5.5 Instant.