====== Key Differences Between Claude Opus and Sonnet ======

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. ((source [[https://www.nxcode.io/resources/news/claude-sonnet-4-6-vs-opus-4-6-complete-comparison-2026|NxCode - Sonnet 4.6 vs Opus 4.6 Comparison]]))

===== Quick Comparison =====

^ Dimension ^ Sonnet 4.6 ^ Opus 4.6 ^
| Input price | $3 per 1M tokens | $15 per 1M tokens |
| Output price | $15 per 1M tokens | $75 per 1M tokens |
| Cost multiplier | 1x (baseline) | 5x |
| SWE-bench Verified (coding) | 79.6% | 80.8% |
| GPQA Diamond (PhD-level science) | 74.1% | 91.3% |
| OSWorld-Verified (computer use) | 72.5% | 72.7% |
| Standard context window | 200K tokens | 200K tokens |
| Extended context (beta) | Not available | 1M tokens |
| Agent Teams | Not available | Supported |
| Extended thinking | Not available | Supported |
| Response speed | Fast | Slower |

((source [[https://www.nxcode.io/resources/news/claude-sonnet-4-6-vs-opus-4-6-complete-comparison-2026|NxCode - Sonnet 4.6 vs Opus 4.6 Comparison]]))

===== Coding Performance =====

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. ((source [[https://www.nxcode.io/resources/news/claude-sonnet-4-6-vs-opus-4-6-complete-comparison-2026|NxCode - Sonnet 4.6 vs Opus 4.6 Comparison]]))

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. ((source [[https://webscraft.org/blog/claude-sonnet-46-vs-opus-46-povne-porivnyannya?lang=en|WebsCraft - Sonnet 4.6 vs Opus 4.6]]))

===== Reasoning and Science =====

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. ((source [[https://www.nxcode.io/resources/news/claude-sonnet-4-6-vs-opus-4-6-complete-comparison-2026|NxCode - Sonnet 4.6 vs Opus 4.6 Comparison]]))

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. ((source [[https://webscraft.org/blog/claude-sonnet-46-vs-opus-46-povne-porivnyannya?lang=en|WebsCraft - Sonnet 4.6 vs Opus 4.6]]))

===== Exclusive Opus Features =====

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

((source [[https://www.cosmicjs.com/blog/claude-opus-46-vs-opus-45-a-real-world-comparison|CosmicJS - Opus 4.6 vs 4.5]]))

===== Version Evolution =====

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

^ Generation ^ Sonnet SWE-bench ^ Opus SWE-bench ^ Gap ^
| Claude 4.5 | 77.2% | 80.9% | 3.7 points |
| Claude 4.6 | 79.6% | 80.8% | 1.2 points |

This trend reflects Anthropic strategy of pushing Sonnet capabilities upward while reserving exclusive features for Opus. ((source [[https://www.nxcode.io/resources/news/claude-sonnet-4-6-vs-opus-4-6-complete-comparison-2026|NxCode - Sonnet 4.6 vs Opus 4.6 Comparison]]))

===== When to Use Each =====

**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

((source [[https://www.nxcode.io/resources/news/claude-sonnet-4-6-vs-opus-4-6-complete-comparison-2026|NxCode - Sonnet 4.6 vs Opus 4.6 Comparison]]))

===== Decision Framework =====

  * **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. ((source [[https://morphllm.com/best-ai-model-for-coding|MorphLLM - Best AI Model for Coding]]))

===== See Also =====

  * [[claude|Claude by Anthropic]]
  * [[chatgpt_claude_gemini_comparison|ChatGPT, Claude, and Gemini Comparison]]
  * [[ai_prompting_technique|AI Prompting Techniques]]
  * [[gemini_fast_thinking_pro|Gemini Flash, Thinking, and Pro]]

===== References =====