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Claude Sonnet 4.5 vs o3
Comprehensive side-by-side LLM comparison
Claude Sonnet 4.5 leads with 2.9% higher average benchmark score. o3 offers 36.0K more tokens in context window than Claude Sonnet 4.5. o3 is $8.00 cheaper per million tokens. Both models have their strengths depending on your specific coding needs.
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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
o3 represents the next generation in OpenAI's reasoning model series, developed to advance the capabilities of deliberate, step-by-step problem solving. Built to handle increasingly complex challenges across mathematics, science, and coding, it continues the evolution of reasoning-focused AI with improved analytical depth and accuracy.
5 months newer
o3
OpenAI
2025-04-16
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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o3
Input:$2.00
Output:$8.00($8.00 cheaper)
Performance Metrics
Context window and performance specifications
Average performance across 3 common benchmarks
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Claude Sonnet 4.5
Average Score:82.5%(+2.9%)
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o3
Average Score:79.6%
Performance comparison across key benchmark categories
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Claude Sonnet 4.5
Coding77.2%(+8.1%)
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o3
Coding69.1%
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Knowledge Cutoff
Training data recency comparison
o3
2024-05-31
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:82.5%(+2.9%)
Providers:2
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o3
Avg Score:79.6%
Providers:1