Model Comparison

GPT-4o mini vs GPT OSS 20B

GPT OSS 20B significantly outperforms across most benchmarks. GPT OSS 20B is 3.0x cheaper per token.

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Performance Benchmarks

Comparative analysis across standard metrics

2 benchmarks

GPT-4o mini outperforms in 0 benchmarks, while GPT OSS 20B is better at 2 benchmarks (GPQA, MMLU).

GPT OSS 20B significantly outperforms across most benchmarks.

Fri May 22 2026 • llm-stats.com

Arena Performance

Human preference votes

Pricing Analysis

Price comparison per million tokens

GPT OSS 20B costs less

For input processing, GPT-4o mini ($0.15/1M tokens) is 3.0x more expensive than GPT OSS 20B ($0.05/1M tokens).

For output processing, GPT-4o mini ($0.60/1M tokens) is 3.0x more expensive than GPT OSS 20B ($0.20/1M tokens).

In conclusion, GPT-4o mini is more expensive than GPT OSS 20B.*

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

Lowest available price from all providers
Fri May 22 2026 • llm-stats.com
OpenAI
GPT-4o mini
Input tokens$0.15
Output tokens$0.60
Best providerAzure
OpenAI
GPT OSS 20B
Input tokens$0.05
Output tokens$0.20
Best providerNovita
Notice missing or incorrect data?Start an Issue→

Context Window

Maximum input and output token capacity

GPT OSS 20B accepts 131,072 input tokens compared to GPT-4o mini's 128,000 tokens. GPT OSS 20B can generate longer responses up to 32,768 tokens, while GPT-4o mini is limited to 16,384 tokens.

OpenAI
GPT-4o mini
Input128,000 tokens
Output16,384 tokens
OpenAI
GPT OSS 20B
Input131,072 tokens
Output32,768 tokens
Fri May 22 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

GPT-4o mini supports multimodal inputs, whereas GPT OSS 20B does not.

GPT-4o mini can handle both text and other forms of data like images, making it suitable for multimodal applications.

GPT-4o mini

Text
Images
Audio
Video

GPT OSS 20B

Text
Images
Audio
Video

License

Usage and distribution terms

GPT-4o mini is licensed under a proprietary license, while GPT OSS 20B uses Apache 2.0.

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

GPT-4o mini

Proprietary

Closed source

GPT OSS 20B

Apache 2.0

Open weights

Release Timeline

When each model was launched

GPT-4o mini was released on 2024-07-18, while GPT OSS 20B was released on 2025-08-05.

GPT OSS 20B is 13 months newer than GPT-4o mini.

GPT-4o mini

Jul 18, 2024

1.8 years ago

GPT OSS 20B

Aug 5, 2025

9 months ago

1.0yr newer

Knowledge Cutoff

When training data ends

GPT-4o mini has a documented knowledge cutoff of 2023-10-01, while GPT OSS 20B's cutoff date is not specified.

We can confirm GPT-4o mini's training data extends to 2023-10-01, but cannot make a direct comparison without GPT OSS 20B's cutoff date.

GPT-4o mini

Oct 2023

GPT OSS 20B

—

Provider Availability

GPT-4o mini is available from Azure. GPT OSS 20B is available from Novita, Fireworks, Groq, OpenAI.

GPT-4o mini

azure logo
Azure
Input Price:Input: $0.15/1MOutput Price:Output: $0.60/1M

GPT OSS 20B

novita logo
Novita
Input Price:Input: $0.05/1MOutput Price:Output: $0.20/1M
fireworks logo
Fireworks
Input Price:Input: $0.10/1MOutput Price:Output: $0.50/1M
groq logo
Groq
Input Price:Input: $0.10/1MOutput Price:Output: $0.50/1M
openai logo
OpenAI
Input Price:Input: $0.10/1MOutput Price:Output: $0.50/1M
* Prices shown are per million tokens

Outputs Comparison

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Key Takeaways

OpenAI
Supports multimodal inputs
OpenAI
Larger context window (131,072 tokens)
Less expensive input tokens
Less expensive output tokens
Has open weights
Higher GPQA score (71.5% vs 40.2%)
Higher MMLU score (85.3% vs 82.0%)

Detailed Comparison

AI Model Comparison Table
Feature
OpenAI
GPT-4o mini
OpenAI
GPT OSS 20B

FAQ

Common questions about GPT-4o mini vs GPT OSS 20B.

Which is better, GPT-4o mini or GPT OSS 20B?

GPT OSS 20B significantly outperforms across most benchmarks. GPT-4o mini is made by OpenAI and GPT OSS 20B is made by OpenAI. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.

How does GPT-4o mini compare to GPT OSS 20B in benchmarks?

GPT-4o mini scores HumanEval: 87.2%, MGSM: 87.0%, MMLU: 82.0%, DROP: 79.7%, MATH: 70.2%. GPT OSS 20B scores MMLU: 85.3%, CodeForces: 74.3%, GPQA: 71.5%, TAU-bench Retail: 54.8%, HealthBench: 42.5%.

Is GPT-4o mini cheaper than GPT OSS 20B?

GPT OSS 20B is 3.0x cheaper for input tokens. GPT-4o mini costs $0.15/M input and $0.60/M output via azure. GPT OSS 20B costs $0.05/M input and $0.20/M output via novita.

What are the context window sizes for GPT-4o mini and GPT OSS 20B?

GPT-4o mini supports 128K tokens and GPT OSS 20B supports 131K tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between GPT-4o mini and GPT OSS 20B?

Key differences include context window (128K vs 131K), input pricing ($0.15 vs $0.05/M), multimodal support (yes vs no), licensing (Proprietary vs Apache 2.0). See the full comparison above for benchmark-by-benchmark results.