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Claude Sonnet 4.5 vs GPT OSS 20B
Comprehensive side-by-side LLM comparison
Claude Sonnet 4.5 leads with 21.7% higher average benchmark score. Claude Sonnet 4.5 offers 1.9K more tokens in context window than GPT OSS 20B. GPT OSS 20B is $17.75 cheaper per million tokens. Claude Sonnet 4.5 supports multimodal inputs. GPT OSS 20B is available on 4 providers. Overall, Claude Sonnet 4.5 is the stronger choice for coding tasks.
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Anthropic
Claude Sonnet 4.5 was developed to bridge human thinking and machine assistance, allowing people to work with language and tools in a more conversational and natural way. Built with a focus on turning ideas into results, it represents an evolution in making AI feel less mechanical while maintaining strong capabilities across reasoning, coding, and collaborative tasks.
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OpenAI
GPT-OSS 20B was created as a smaller open-source variant, designed to balance capability with accessibility for researchers and developers. Built with 20 billion parameters, it provides a more approachable entry point for those seeking to work with open-source language models while benefiting from OpenAI's architectural insights.
1 month newer
GPT OSS 20B
OpenAI
2025-08-05
Claude Sonnet 4.5
Anthropic
2025-09-29
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Pricing Comparison
Cost per million tokens (USD)
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Claude Sonnet 4.5
Input:$3.00
Output:$15.00
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GPT OSS 20B
Input:$0.05
Output:$0.20($17.75 cheaper)
Performance Metrics
Context window and performance specifications
Average performance across 2 common benchmarks
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Claude Sonnet 4.5
Average Score:84.8%(+21.7%)
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GPT OSS 20B
Average Score:63.1%
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Knowledge Cutoff
Training data recency comparison
Claude Sonnet 4.5
2025-01-31
More recent knowledge cutoff means awareness of newer technologies and frameworks
Provider Availability & Performance
Available providers and their performance metrics
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Claude Sonnet 4.5
2 providers
Anthropic
Throughput: 42 tok/s
Latency: 0.4ms
ZeroEval
Throughput: 42 tok/s
Latency: 0.4ms
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Claude Sonnet 4.5
Avg Score:84.8%(+21.7%)
Providers:2
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GPT OSS 20B
Avg Score:63.1%
Providers:4