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Claude Sonnet 4.5 vs o3
Comprehensive side-by-side LLM comparison
o3 leads with 2.4% higher average benchmark score. o3 offers 36.0K more tokens in context window than Claude Sonnet 4.5. Claude Sonnet 4.5 is $32.00 cheaper per million tokens. Claude Sonnet 4.5 is available on 3 providers. Both models have their strengths depending on your specific coding needs.
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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
OpenAI o3, released by OpenAI in April 2025, is a large reasoning model that applies extended chain-of-thought processing to deliver improved performance on complex math, science, and coding tasks. It features a 200K token context window and native image understanding, with demonstrated strong results on mathematics and software engineering benchmarks. o3 targets demanding analytical and engineering tasks where deliberate, multi-step reasoning produces significantly better outcomes than direct generation.
5 months newer
o3
OpenAI
2025-04-16
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($32.00 cheaper)
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o3
Input:$10.00
Output:$40.00
Performance Metrics
Context window and performance specifications
Average performance across 6 common benchmarks
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Claude Sonnet 4.5
Average Score:41.3%
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o3
Average Score:43.7%(+2.4%)
Performance comparison across key benchmark categories
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Claude Sonnet 4.5
Science83.4%(+14.3%)
Agents51.9%(+25.0%)
Tool Use43.8%(+0.2%)
Reasoning17.7%
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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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o3
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Claude Sonnet 4.5
Avg Score:41.3%
Providers:3
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o3
Avg Score:43.7%(+2.4%)
Providers:1