Model Comparison

GPT-5 vs GPT OSS 20B

GPT-5 shows notably better performance in the majority of benchmarks. GPT OSS 20B is 39.3x cheaper per token.

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Performance Benchmarks

Comparative analysis across standard metrics

4 benchmarks

GPT-5 outperforms in 3 benchmarks (GPQA, Humanity's Last Exam, MMLU), while GPT OSS 20B is better at 1 benchmark (HealthBench Hard).

GPT-5 shows notably better performance in the majority of benchmarks.

Sat Apr 25 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-5 ($1.25/1M tokens) is 25.0x more expensive than GPT OSS 20B ($0.05/1M tokens).

For output processing, GPT-5 ($10.00/1M tokens) is 50.0x more expensive than GPT OSS 20B ($0.20/1M tokens).

In conclusion, GPT-5 is more expensive than GPT OSS 20B.*

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

Lowest available price from all providers
Sat Apr 25 2026 • llm-stats.com
OpenAI
GPT-5
Input tokens$1.25
Output tokens$10.00
Best providerOpenAI
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-5 accepts 400,000 input tokens compared to GPT OSS 20B's 131,072 tokens. GPT-5 can generate longer responses up to 128,000 tokens, while GPT OSS 20B is limited to 32,768 tokens.

OpenAI
GPT-5
Input400,000 tokens
Output128,000 tokens
OpenAI
GPT OSS 20B
Input131,072 tokens
Output32,768 tokens
Sat Apr 25 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

GPT-5 supports multimodal inputs, whereas GPT OSS 20B does not.

GPT-5 can handle both text and other forms of data like images, making it suitable for multimodal applications.

GPT-5

Text
Images
Audio
Video

GPT OSS 20B

Text
Images
Audio
Video

License

Usage and distribution terms

GPT-5 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-5

Proprietary

Closed source

GPT OSS 20B

Apache 2.0

Open weights

Release Timeline

When each model was launched

GPT-5 was released on 2025-08-07, while GPT OSS 20B was released on 2025-08-05.

GPT-5 is 0 month newer than GPT OSS 20B.

GPT-5

Aug 7, 2025

8 months ago

2d newer
GPT OSS 20B

Aug 5, 2025

8 months ago

Knowledge Cutoff

When training data ends

GPT-5 has a documented knowledge cutoff of 2024-09-30, while GPT OSS 20B's cutoff date is not specified.

We can confirm GPT-5's training data extends to 2024-09-30, but cannot make a direct comparison without GPT OSS 20B's cutoff date.

GPT-5

Sep 2024

GPT OSS 20B

—

Provider Availability

GPT-5 is available from OpenAI. GPT OSS 20B is available from Novita, Fireworks, Groq, OpenAI.

GPT-5

openai logo
OpenAI
Input Price:Input: $1.25/1MOutput Price:Output: $10.00/1M

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
Larger context window (400,000 tokens)
Supports multimodal inputs
Higher GPQA score (85.7% vs 71.5%)
Higher Humanity's Last Exam score (24.8% vs 10.9%)
Higher MMLU score (92.5% vs 85.3%)
OpenAI
Less expensive input tokens
Less expensive output tokens
Has open weights
Higher HealthBench Hard score (10.8% vs 1.6%)

Detailed Comparison

AI Model Comparison Table
Feature
OpenAI
GPT-5
OpenAI
GPT OSS 20B

FAQ

Common questions about GPT-5 vs GPT OSS 20B

GPT-5 shows notably better performance in the majority of benchmarks. GPT-5 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.
GPT-5 scores SWE-Lancer (IC-Diamond subset): 100.0%, COLLIE: 99.0%, Tau2 Telecom: 96.7%, OpenAI-MRCR: 2 needle 128k: 95.2%, AIME 2025: 94.6%. GPT OSS 20B scores MMLU: 85.3%, CodeForces: 74.3%, GPQA: 71.5%, TAU-bench Retail: 54.8%, HealthBench: 42.5%.
GPT OSS 20B is 25.0x cheaper for input tokens. GPT-5 costs $1.25/M input and $10.00/M output via openai. GPT OSS 20B costs $0.05/M input and $0.20/M output via novita.
GPT-5 supports 400K tokens and GPT OSS 20B supports 131K tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.
Key differences include context window (400K vs 131K), input pricing ($1.25 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.