Model Comparison

GPT OSS 20B vs Magistral Small 2506Which is better in 2026?

GPT OSS 20B significantly outperforms across most benchmarks.

Verdict: GPT OSS 20B vs Magistral Small 2506 — which is better?

GPT OSS 20B (by OpenAI) and Magistral Small 2506 (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 OSS 20B outperforms in 1 benchmarks (GPQA), while Magistral Small 2506 is better at 0 benchmarks. GPT OSS 20B significantly outperforms across most benchmarks.

Choose GPT OSS 20B if…

  • you want the strongest raw capability — it leads on 1 of 1 shared benchmarks
  • you want the most recent training data — it shipped Aug 2025

Choose Magistral Small 2506 if…

  • you are already invested in the Mistral AI ecosystem
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Performance Benchmarks

Comparative analysis across standard metrics

1 benchmarks

GPT OSS 20B outperforms in 1 benchmarks (GPQA), while Magistral Small 2506 is better at 0 benchmarks.

GPT OSS 20B significantly outperforms across most benchmarks.

Sun Jun 14 2026 • llm-stats.com

Arena Performance

Human preference votes

Model Size

Parameter count comparison

3.1B diff

Magistral Small 2506 has 3.1B more parameters than GPT OSS 20B, making it 14.8% larger.

OpenAI
GPT OSS 20B
20.9Bparameters
Mistral AI
Magistral Small 2506
24.0Bparameters
20.9B
GPT OSS 20B
24.0B
Magistral Small 2506

Context Window

Maximum input and output token capacity

Only GPT OSS 20B specifies input context (131,072 tokens). Only GPT OSS 20B specifies output context (32,768 tokens).

OpenAI
GPT OSS 20B
Input131,072 tokens
Output32,768 tokens
Mistral AI
Magistral Small 2506
Input- tokens
Output- tokens
Sun Jun 14 2026 • llm-stats.com

License

Usage and distribution terms

Both models are licensed under Apache 2.0.

Both models share the same licensing terms, providing consistent usage rights.

GPT OSS 20B

Apache 2.0

Open weights

Magistral Small 2506

Apache 2.0

Open weights

Release Timeline

When each model was launched

GPT OSS 20B was released on 2025-08-05, while Magistral Small 2506 was released on 2025-06-10.

GPT OSS 20B is 2 months newer than Magistral Small 2506.

GPT OSS 20B

Aug 5, 2025

10 months ago

1mo newer
Magistral Small 2506

Jun 10, 2025

1.0 years ago

Knowledge Cutoff

When training data ends

Magistral Small 2506 has a documented knowledge cutoff of 2025-06-01, while GPT OSS 20B's cutoff date is not specified.

We can confirm Magistral Small 2506's training data extends to 2025-06-01, but cannot make a direct comparison without GPT OSS 20B's cutoff date.

GPT OSS 20B

—

Magistral Small 2506

Jun 2025

Outputs Comparison

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Key Takeaways

OpenAI
Larger context window (131,072 tokens)
Higher GPQA score (71.5% vs 68.2%)
Mistral AI

No standout differentiators in the data we have for this pair.

Detailed Comparison

AI Model Comparison Table
Feature
OpenAI
GPT OSS 20B
Mistral AI
Magistral Small 2506

FAQ

Common questions about GPT OSS 20B vs Magistral Small 2506.

Which is better, GPT OSS 20B or Magistral Small 2506?

GPT OSS 20B significantly outperforms across most benchmarks. GPT OSS 20B is made by OpenAI and Magistral Small 2506 is made by Mistral AI. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.

How does GPT OSS 20B compare to Magistral Small 2506 in benchmarks?

GPT OSS 20B scores MMLU: 85.3%, CodeForces: 74.3%, GPQA: 71.5%, TAU-bench Retail: 54.8%, HealthBench: 42.5%. Magistral Small 2506 scores AIME 2024: 70.7%, GPQA: 68.2%, AIME 2025: 62.8%, LiveCodeBench: 51.3%.

What are the context window sizes for GPT OSS 20B and Magistral Small 2506?

GPT OSS 20B supports 131K tokens and Magistral Small 2506 supports an unknown number of tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

Who makes GPT OSS 20B and Magistral Small 2506?

GPT OSS 20B is developed by OpenAI and Magistral Small 2506 is developed by Mistral AI.

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