When facing complex problems, you can unlock Claude's deeper reasoning capabilities using extended thinking modes. These special keywords actually trigger additional computation time, giving Claude more "thinking budget" to evaluate alternatives thoroughly.
Extended thinking mode is a "hidden mode" feature that's documented in Anthropic's Claude Code best practices guide.
The Thinking Hierarchy
These phrases map directly to increasing levels of thinking budget:
- "think" - Basic enhanced reasoning
- "think hard" - More computation time
- "think harder" - Significant reasoning boost
- "ultrathink" - Maximum thinking budget
When you type these keywords in Claude Code, they actually change color in the interface - that's your visual cue that you're unlocking extra reasoning power.
Perfect with Plan Mode
Extended thinking modes work exceptionally well with Plan Mode. Start your planning sessions like this:
think hard about the best approach for implementing user authentication
with SSO integration, considering security, scalability, and user experience
The combination is powerful because:
- Plan Mode prevents Claude from jumping straight to code
- Extended thinking ensures thorough analysis before implementation
- You get a well-reasoned plan before any changes are made
Example Usage
Architecture Decisions
ultrathink about the database schema design for this multi-tenant SaaS,
considering data isolation, query performance, backup strategies, and
future scaling requirements
Debugging Complex Issues
think harder about why this React component is re-rendering unexpectedly.
Analyze the props, state, and context usage to identify the root cause
Approach Evaluation
think about the trade-offs between implementing this as a microservice
versus adding it to the existing monolith
Best Practices
✅ When to Use Extended Thinking
- Complex architectural decisions
- Debugging tricky problems that aren't obvious
- Evaluating multiple implementation approaches
- Planning large features with many moving parts
- Security-sensitive implementations
❌ When NOT to Use Extended Thinking
- Simple, straightforward tasks
- Basic CRUD operations
- Obvious bug fixes
- Simple styling changes
Budget Considerations
Extended thinking modes use more of your usage budget. Use them strategically:
- Start with "think" and escalate only if needed
- Save "ultrathink" for genuinely complex problems
- Don't use for every simple question