Model Comparison

Claude Opus 4.5 vs GPT OSS 20B

Claude Opus 4.5 significantly outperforms across most benchmarks. GPT OSS 20B is 114.3x cheaper per token.

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Performance Benchmarks

Comparative analysis across standard metrics

1 benchmarks

Claude Opus 4.5 outperforms in 1 benchmarks (GPQA), while GPT OSS 20B is better at 0 benchmarks.

Claude Opus 4.5 significantly outperforms across most benchmarks.

Wed Apr 15 2026 • llm-stats.com

Arena Performance

Human preference votes

Pricing Analysis

Price comparison per million tokens

GPT OSS 20B costs less

For input processing, Claude Opus 4.5 ($5.00/1M tokens) is 100.0x more expensive than GPT OSS 20B ($0.05/1M tokens).

For output processing, Claude Opus 4.5 ($25.00/1M tokens) is 125.0x more expensive than GPT OSS 20B ($0.20/1M tokens).

In conclusion, Claude Opus 4.5 is more expensive than GPT OSS 20B.*

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

Lowest available price from all providers
Wed Apr 15 2026 • llm-stats.com
Anthropic
Claude Opus 4.5
Input tokens$5.00
Output tokens$25.00
Best providerAnthropic
OpenAI
GPT OSS 20B
Input tokens$0.05
Output tokens$0.20
Best providerNovita
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Context Window

Maximum input and output token capacity

Claude Opus 4.5 accepts 200,000 input tokens compared to GPT OSS 20B's 131,072 tokens. Claude Opus 4.5 can generate longer responses up to 64,000 tokens, while GPT OSS 20B is limited to 32,768 tokens.

Anthropic
Claude Opus 4.5
Input200,000 tokens
Output64,000 tokens
OpenAI
GPT OSS 20B
Input131,072 tokens
Output32,768 tokens
Wed Apr 15 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Claude Opus 4.5 supports multimodal inputs, whereas GPT OSS 20B does not.

Claude Opus 4.5 can handle both text and other forms of data like images, making it suitable for multimodal applications.

Claude Opus 4.5

Text
Images
Audio
Video

GPT OSS 20B

Text
Images
Audio
Video

License

Usage and distribution terms

Claude Opus 4.5 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.

Claude Opus 4.5

Proprietary

Closed source

GPT OSS 20B

Apache 2.0

Open weights

Release Timeline

When each model was launched

Claude Opus 4.5 was released on 2025-11-24, while GPT OSS 20B was released on 2025-08-05.

Claude Opus 4.5 is 4 months newer than GPT OSS 20B.

Claude Opus 4.5

Nov 24, 2025

4 months ago

3mo newer
GPT OSS 20B

Aug 5, 2025

8 months ago

Knowledge Cutoff

When training data ends

Claude Opus 4.5 has a documented knowledge cutoff of 2025-03-31, while GPT OSS 20B's cutoff date is not specified.

We can confirm Claude Opus 4.5's training data extends to 2025-03-31, but cannot make a direct comparison without GPT OSS 20B's cutoff date.

Claude Opus 4.5

Mar 2025

GPT OSS 20B

—

Provider Availability

Claude Opus 4.5 is available from Anthropic. GPT OSS 20B is available from Novita, Fireworks, Groq, OpenAI.

Claude Opus 4.5

anthropic logo
Anthropic
Input Price:Input: $5.00/1MOutput Price:Output: $25.00/1M

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

Anthropic
Larger context window (200,000 tokens)
Supports multimodal inputs
Higher GPQA score (87.0% vs 71.5%)
OpenAI
Less expensive input tokens
Less expensive output tokens
Has open weights

Detailed Comparison

AI Model Comparison Table
Feature
Anthropic
Claude Opus 4.5
OpenAI
GPT OSS 20B

FAQ

Common questions about Claude Opus 4.5 vs GPT OSS 20B

Claude Opus 4.5 significantly outperforms across most benchmarks. Claude Opus 4.5 is made by Anthropic and GPT OSS 20B is made by OpenAI. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.
Claude Opus 4.5 scores Tau2 Telecom: 98.2%, MMMLU: 90.8%, Tau2 Retail: 88.9%, GPQA: 87.0%, SWE-Bench Verified: 80.9%. 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 100.0x cheaper for input tokens. Claude Opus 4.5 costs $5.00/M input and $25.00/M output via anthropic. GPT OSS 20B costs $0.05/M input and $0.20/M output via novita.
Claude Opus 4.5 supports 200K 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 (200K vs 131K), input pricing ($5.00 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.
Claude Opus 4.5 is developed by Anthropic and GPT OSS 20B is developed by OpenAI.