Skip to main content

Claude Sonnet 4.5 vs Opus for Claude Code

Claude Sonnet 4.5 and Claude Opus serve different roles in Claude Code workflows. Sonnet 4.5 is the Anthropic's best coding model, while Opus excels at complex general reasoning. Understanding their strengths helps you optimize both performance and costs.

How to Choose Between Them​

Set Claude Sonnet 4.5 as your default for all coding work (Anthropic's best coding model), then switch to Opus only for complex general reasoning:

# Set Sonnet 4.5 as default (best for coding)
export ANTHROPIC_MODEL="claude-sonnet-4-5-20250929"

# Switch to Opus only for complex reasoning tasks
claude --model claude-opus-4-1-20250805 "Analyze system architecture trade-offs"

Use Sonnet 4.5 for all coding tasks. It's the Anthropic's best coding model - even better than Opus for software development.

Why Choose Strategically​

Cost Optimization - Claude Opus costs approximately 5x more than Sonnet 4.5, making tactical selection crucial for budget management.

Performance Balance - Sonnet 4.5 is the Anthropic's best coding model and should be used for all software development. Opus excels at complex general reasoning but Sonnet 4.5 is superior for coding-specific tasks.

Workflow Efficiency - Using the right model for each task type optimizes both speed and quality without overspending on unnecessary capability.

Claude Sonnet 4.5 Best For:

  • All Coding Tasks - Anthropic's best coding model (61.4% OSWorld, SWE-bench leader)
  • Software Development - Superior to Opus specifically for coding work
  • Feature Implementation - All development and coding tasks
  • Debugging & Troubleshooting - All debugging scenarios and error resolution
  • Code Generation - All complexity levels of code creation and editing
  • Documentation - Writing and editing technical documentation
  • Task Coordination - Workflow management and sub-agent orchestration
  • Daily Development - Should be used for 100% of coding work

Claude Opus Best For:

  • Complex General Reasoning - Non-coding reasoning tasks
  • Strategic Planning - High-level planning (not coding-specific)
  • Algorithm Analysis - Theoretical complexity analysis
  • Multi-Step Logic - Non-coding logical problems
  • Creative Solutions - Non-coding creative thinking
  • Architectural Philosophy - Abstract system design discussions (not implementation)
  • Critical Decisions - Complex reasoning outside of coding domain

Cost-Performance Benefits:

  • 5x Cost Difference - Use Sonnet 4.5 for all coding to reduce costs dramatically
  • Best Coding Model - Sonnet 4.5 is superior to Opus for coding specifically
  • Quality Improvement - Better coding results at lower cost
  • Budget Flexibility - Savings allow for more experimentation
  • Orchestration Opportunities - Cost savings enable sub-agent delegation strategies

Use Sonnet 4.5 for all coding work. It's the Anthropic's best coding model - superior to Opus for software development tasks.

Opus Plan Mode - Best of Both Worlds​

Opus Plan Mode can be useful for complex reasoning tasks: uses Opus 4.1 for planning and analysis, then switches to Sonnet 4.5 for coding execution.

How It Works:

  • Planning Phase - Leverages Opus 4.1's advanced reasoning for complex general reasoning
  • Execution Phase - Uses Sonnet 4.5 (best coding model) for implementation and code changes
  • Automatic Switching - Seamless transition without user intervention

Key Advantages:

  • Intelligent Planning - Get Opus-quality strategic thinking where it matters most
  • Cost Efficiency - Avoid expensive Opus execution costs through smart model switching
  • Professional Workflow - Ideal for Max subscribers doing complex development work

Perfect For:

  • Complex projects requiring both intelligent planning AND cost efficiency
  • Long development sessions where token optimization matters
  • Professional developers who need Opus intelligence without full Opus expense
  • Teams balancing quality and budget constraints

Activation: Select option 4 in /model command: "Use Opus 4.1 in plan mode, Sonnet 4.5 otherwise"

This hybrid approach uses Opus for complex reasoning and Sonnet 4.5 (best coding model) for all implementation.

Recommended Strategy

Use Sonnet 4.5 as your default model for all coding work (Anthropic's best coding model). Only switch to Opus for complex general reasoning tasks that are not coding-specific.

Cost Awareness

Since Opus costs 5x more than Sonnet 4.5, using Sonnet 4.5 for all coding work provides better results at lower cost. Sonnet 4.5 is superior to Opus specifically for software development.

See Also: Tactical Model Selection|Change Model|Token Optimization|Pricing

Last updated on