Claude 4.5 Opus vs Sonnet: Choosing the Right Model

Choosing the Right Claude Model

Anthropic's Claude family offers distinct models for different use cases. Here's a practical guide for developers.

Opus: The Reasoning Powerhouse

Use Claude Opus when you need:

• Complex multi-step reasoning
• Code generation with architectural awareness
• Nuanced analysis of technical documents
• Tasks where accuracy matters more than speed

Sonnet: The Speed-Quality Balance

Use Claude Sonnet when you need:

• Fast responses for interactive applications
• High-volume processing at lower cost
• Chat-based interfaces where latency matters
• Tasks that are well-defined and structured

Benchmark Comparison

| Task | Opus | Sonnet | | ------------------ | ---- | ------ | | Code generation | 94% | 89% | | Reasoning | 97% | 91% | | Speed (tokens/s) | 45 | 120 | | Cost per 1M tokens | $15 | $3 |

The Practical Strategy

function selectModel(task: Task): Model {
  if (task.requiresDeepReasoning || task.isArchitectural) {
    return "claude-opus-4";
  }
  return "claude-sonnet-4";
}

Don't default to the most powerful model. Match the model to the task — your wallet and your users will thank you.

Bottom Line

Opus for thinking, Sonnet for doing. Most production applications benefit from using both strategically.