Claude Opus and Claude Sonnet are Anthropic two main model tiers, with Opus as the premium flagship and Sonnet as the high-performance mid-tier. As of early 2026, Sonnet 4.6 delivers 98 percent of Opus coding performance at one-fifth the cost, making the choice between them one of the most common decisions developers face. ¹⁾

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The coding gap between Sonnet and Opus has narrowed dramatically across versions. On SWE-bench Verified, Sonnet 4.6 scores 79.6 percent versus Opus 4.6 at 80.8 percent, a negligible 1.2-point difference. Sonnet 4.6 actually outperforms all prior Opus models on coding benchmarks. ³⁾

Sonnet is described as less lazy with cleaner code generation and better prompt adherence, and was preferred 59 to 70 percent over Opus 4.5 in developer tests. ⁴⁾

The biggest gap between the two models appears in expert-level reasoning. On GPQA Diamond, which tests PhD-level physics, chemistry, and biology, Opus 4.6 scores 91.3 percent versus Sonnet at 74.1 percent, a massive 17.2-point difference. ⁵⁾

Opus also leads on Terminal-Bench 2.0 (65.4 percent vs approximately 59 percent) and ARC-AGI-2 (approximately 68.8 percent vs 60.4 percent), demonstrating its edge in novel reasoning and long-context terminal tasks. ⁶⁾

Opus 4.6 offers several capabilities not available in Sonnet:

• Agent Teams: Enables parallel, multi-agent workflows where multiple Claude instances collaborate on complex tasks
• Extended Thinking: Deeper analysis mode for complex problems requiring sustained reasoning
• 1M Token Context Window (beta): Opus scores 76 percent on 8-needle 1M MRCR v2 versus Sonnet 4.5 at 18.5 percent, demonstrating dramatically superior long-context performance
• Adaptive Thinking: Autonomously determines reasoning depth for each problem

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The gap between Sonnet and Opus has narrowed consistently across generations:

This trend reflects Anthropic strategy of pushing Sonnet capabilities upward while reserving exclusive features for Opus. ⁸⁾

Choose Sonnet 4.6 (80 to 90 percent of scenarios):

• Most coding tasks (bugs, features, tests)
• Computer automation and GUI tasks
• Instruction following and data analysis
• High-volume API usage
• Quick security scans
• Budget-sensitive production workloads

Choose Opus 4.6 (premium scenarios):

• Expert science and research
• Multi-agent workflows using Agent Teams
• Large codebase refactors exceeding 10K lines
• Deep security audits
• PhD-level reasoning tasks
• Ultra-long context analysis

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• Standard coding: Sonnet
• Large refactor: Opus
• GUI and automation: Sonnet
• Science and expert tasks: Opus
• Multi-agent workflows: Opus
• High-volume production: Sonnet (escalate to Opus if needed)

Sonnet 4.6 delivers 95 to 99 percent of Opus quality at 3 to 5x lower cost with a speed advantage, making it the recommended default for the vast majority of use cases. ¹⁰⁾

• Claude by Anthropic
• ChatGPT, Claude, and Gemini Comparison
• AI Prompting Techniques
• Gemini Flash, Thinking, and Pro