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Claude Sonnet 4.5 vs GPT-OSS-20B
Comprehensive side-by-side LLM comparison
Claude Sonnet 4.5 leads with 23.0% higher average benchmark score. Claude Sonnet 4.5 offers 131.9K more tokens in context window than GPT-OSS-20B. Claude Sonnet 4.5 is $Infinity cheaper per million tokens. Claude Sonnet 4.5 supports multimodal inputs. Claude Sonnet 4.5 is available on 3 providers. Overall, Claude Sonnet 4.5 is the stronger choice for coding tasks.
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Anthropic
Claude Sonnet 4.5, released by Anthropic in September 2025, is a large language model from the Claude 4.5 family that balances response quality and efficiency for coding, agentic tasks, and analytical work. It features a 200K token context window (extendable to 1M tokens in beta), 64K maximum output tokens, native image understanding, and extended thinking support. Sonnet 4.5 targets use cases that require a balance of throughput and reasoning depth, including code generation, data analysis, and multi-step agentic pipelines.
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OpenAI
GPT-OSS-20B is an open-weight large language model with 20 billion parameters from OpenAI's open-source model initiative. It targets deployments requiring a smaller, efficient model that can run on consumer or mid-tier hardware while maintaining strong reasoning and coding capabilities relative to its size.
1 month newer
GPT-OSS-20B
OpenAI
2025-08-05
Claude Sonnet 4.5
Anthropic
2025-09-29
Pricing Comparison
Cost per million tokens (USD)
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Claude Sonnet 4.5
Input:$3.00
Output:$15.00($Infinity cheaper)
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GPT-OSS-20B
Input:$Infinity
Output:$Infinity
Performance Metrics
Context window and performance specifications
Average performance across 2 common benchmarks
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Claude Sonnet 4.5
Average Score:63.7%(+23.0%)
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GPT-OSS-20B
Average Score:40.7%
Performance comparison across key benchmark categories
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Claude Sonnet 4.5
Science83.4%(+3.3%)
Agents43.9%(+42.6%)
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GPT-OSS-20B
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Knowledge Cutoff
Training data recency comparison
Claude Sonnet 4.5
2025-01
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
3 providers
Anthropic
AWS Bedrock
Google Cloud Vertex AI
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GPT-OSS-20B
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Claude Sonnet 4.5
Avg Score:63.7%(+23.0%)
Providers:3
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GPT-OSS-20B
Avg Score:40.7%
Providers:1