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Claude Opus 4.5 vs o3
Comprehensive side-by-side LLM comparison
Claude Opus 4.5 leads with 4.8% higher average benchmark score. o3 offers 36.0K more tokens in context window than Claude Opus 4.5. Claude Opus 4.5 is $20.00 cheaper per million tokens. Claude Opus 4.5 is available on 3 providers. Both models have their strengths depending on your specific coding needs.
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Anthropic
Claude Opus 4.5, released by Anthropic in November 2025, is a large language model from the Claude 4.5 family built for demanding reasoning tasks, advanced code generation, and complex agentic workflows. It features a 200K token context window, 64K maximum output tokens, native image understanding, and extended thinking with configurable effort levels. Opus 4.5 targets deep analytical work, multi-step tool orchestration, and applications requiring sustained reasoning across long, complex tasks.
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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.
6 months newer
o3
OpenAI
2025-04-16
Claude Opus 4.5
Anthropic
2025-11-01
Pricing Comparison
Cost per million tokens (USD)
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Claude Opus 4.5
Input:$5.00
Output:$25.00($20.00 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 Opus 4.5
Average Score:48.5%(+4.8%)
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o3
Average Score:43.7%
Performance comparison across key benchmark categories
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Claude Opus 4.5
Science87.0%(+17.9%)
Tool Use62.3%(+18.7%)
Agents55.9%(+29.0%)
Reasoning30.8%(+11.6%)
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Knowledge Cutoff
Training data recency comparison
Claude Opus 4.5
2025-05
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 Opus 4.5
3 providers
Anthropic
AWS Bedrock
Google Cloud Vertex AI
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o3
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Claude Opus 4.5
Avg Score:48.5%(+4.8%)
Providers:3
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o3
Avg Score:43.7%
Providers:1