Model Comparison

GPT-5.6 Luna vs Mistral Medium 3.5Which is better in 2026?

GPT-5.6 Luna significantly outperforms across most benchmarks. GPT-5.6 Luna is 1.3x cheaper per token.

Verdict: GPT-5.6 Luna vs Mistral Medium 3.5 — which is better?

GPT-5.6 Luna (by OpenAI) and Mistral Medium 3.5 (by Mistral AI) 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.

GPT-5.6 Luna outperforms in 2 benchmarks (BrowseComp, GDPval-AA), while Mistral Medium 3.5 is better at 0 benchmarks. GPT-5.6 Luna significantly outperforms across most benchmarks.

On price, GPT-5.6 Luna is roughly 1.3x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.

GPT-5.6 Luna also accepts a larger context window (1,050,000 input tokens), making it the stronger choice for long documents and large codebases.

Choose GPT-5.6 Luna if…

  • you want the strongest raw capability — it leads on 2 of 2 shared benchmarks
  • cost matters — it's about 1.3x cheaper per token
  • you process long inputs — it offers a 1,050,000 token context window
  • you want the most recent training data — it shipped Jul 2026

Choose Mistral Medium 3.5 if…

  • you need open weights you can self-host or fine-tune

Performance Benchmarks

Comparative analysis across standard metrics

2 benchmarks

GPT-5.6 Luna outperforms in 2 benchmarks (BrowseComp, GDPval-AA), while Mistral Medium 3.5 is better at 0 benchmarks.

GPT-5.6 Luna significantly outperforms across most benchmarks.

Sun Jul 26 2026 • llm-stats.com

Arena Performance

Human preference votes

Pricing Analysis

Price comparison per million tokens

GPT-5.6 Luna costs less

For input processing, GPT-5.6 Luna ($1.00/1M tokens) is 1.5x cheaper than Mistral Medium 3.5 ($1.50/1M tokens).

For output processing, GPT-5.6 Luna ($6.00/1M tokens) is 1.3x cheaper than Mistral Medium 3.5 ($7.50/1M tokens).

In conclusion, Mistral Medium 3.5 is more expensive than GPT-5.6 Luna.*

* Using a 3:1 ratio of input to output tokens

Lowest available price from all providers
Sun Jul 26 2026 • llm-stats.com
OpenAI
GPT-5.6 Luna
Input tokens$1.00
Output tokens$6.00
Best providerOpenAI
Mistral AI
Mistral Medium 3.5
Input tokens$1.50
Output tokens$7.50
Best providerMistral
Notice missing or incorrect data?Start an Issue→

Context Window

Maximum input and output token capacity

GPT-5.6 Luna accepts 1,050,000 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-5.6 Luna is limited to 128,000 tokens.

OpenAI
GPT-5.6 Luna
Input1,050,000 tokens
Output128,000 tokens
Mistral AI
Mistral Medium 3.5
Input256,000 tokens
Output256,000 tokens
Sun Jul 26 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Both GPT-5.6 Luna and Mistral Medium 3.5 support multimodal inputs.

They are both capable of processing various types of data, offering versatility in application.

GPT-5.6 Luna

Text
Images
Audio
Video

Mistral Medium 3.5

Text
Images
Audio
Video

License

Usage and distribution terms

GPT-5.6 Luna is licensed under a proprietary license, while Mistral Medium 3.5 uses Modified MIT License.

License differences may affect how you can use these models in commercial or open-source projects.

GPT-5.6 Luna

Proprietary

Closed source

Mistral Medium 3.5

Modified MIT License

Open weights

Release Timeline

When each model was launched

GPT-5.6 Luna was released on 2026-07-09, while Mistral Medium 3.5 was released on 2026-04-29.

GPT-5.6 Luna is 2 months newer than Mistral Medium 3.5.

GPT-5.6 Luna

Jul 9, 2026

2 weeks ago

2mo newer
Mistral Medium 3.5

Apr 29, 2026

2 months ago

Knowledge Cutoff

When training data ends

GPT-5.6 Luna has a documented knowledge cutoff of 2026-02-16, while Mistral Medium 3.5's cutoff date is not specified.

We can confirm GPT-5.6 Luna's training data extends to 2026-02-16, but cannot make a direct comparison without Mistral Medium 3.5's cutoff date.

GPT-5.6 Luna

Feb 2026

Mistral Medium 3.5

—

Provider Availability

GPT-5.6 Luna is available from OpenAI. Mistral Medium 3.5 is available from Mistral AI.

GPT-5.6 Luna

openai logo
OpenAI
Input Price:Input: $1.00/1MOutput Price:Output: $6.00/1M

Mistral Medium 3.5

mistral logo
Mistral
Input Price:Input: $1.50/1MOutput Price:Output: $7.50/1M
* Prices shown are per million tokens

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Key Takeaways

OpenAI
Larger context window (1,050,000 tokens)
Less expensive input tokens
Less expensive output tokens
Higher BrowseComp score (83.3% vs 48.6%)
Higher GDPval-AA score (53.1% vs 30.9%)
Mistral AI
Has open weights

Detailed Comparison

Interactive Arena

Judge for yourself.

Run your own prompts against GPT-5.6 Luna and Mistral Medium 3.5 side-by-side, then vote on the output you prefer.

GPT-5.6 Luna
✓ Preferred
Mistral Medium 3.5
Open in Playground
AI Model Comparison Table
Feature
OpenAI
GPT-5.6 Luna
Mistral AI
Mistral Medium 3.5

FAQ

Common questions about GPT-5.6 Luna vs Mistral Medium 3.5.

Which is better, GPT-5.6 Luna or Mistral Medium 3.5?

GPT-5.6 Luna significantly outperforms across most benchmarks. GPT-5.6 Luna is made by OpenAI and Mistral Medium 3.5 is made by Mistral AI. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.

How does GPT-5.6 Luna compare to Mistral Medium 3.5 in benchmarks?

GPT-5.6 Luna scores Connectors: 99.9%, HealthBench Consensus: 95.1%, GPQA: 92.3%, Search and Function-Calling: 89.7%, Capture-the-Flag Challenges (Internal): 85.2%. Mistral Medium 3.5 scores COLLIE: 95.8%, Tau3 Telecom: 91.4%, AIME 2025: 86.3%, SWE-Bench Verified: 77.6%, Tau3 Retail: 76.1%.

Is GPT-5.6 Luna cheaper than Mistral Medium 3.5?

GPT-5.6 Luna is 1.5x cheaper for input tokens. GPT-5.6 Luna costs $1.00/M input and $6.00/M output via openai. Mistral Medium 3.5 costs $1.50/M input and $7.50/M output via mistral.

What are the context window sizes for GPT-5.6 Luna and Mistral Medium 3.5?

GPT-5.6 Luna supports 1.1M tokens and Mistral Medium 3.5 supports 256K tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between GPT-5.6 Luna and Mistral Medium 3.5?

Key differences include context window (1.1M vs 256K), input pricing ($1.00 vs $1.50/M), licensing (Proprietary vs Modified MIT License). See the full comparison above for benchmark-by-benchmark results.

Who makes GPT-5.6 Luna and Mistral Medium 3.5?

GPT-5.6 Luna is developed by OpenAI and Mistral Medium 3.5 is developed by Mistral AI.

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