Overview
Claude Haiku 4.5 is the smallest and fastest model in the Claude family. It's designed for speed and cost efficiency. While it doesn't match Opus or Sonnet for complex reasoning, it's surprisingly capable for straightforward coding tasks and is the go-to for tab completion and quick code generation.
Key Specs
| Spec | Details |
|---|---|
| Model ID | claude-haiku-4-5-20251001 |
| Context Window | 200,000 tokens |
| Max Output | 8,192 tokens per response |
| Input Cost | $0.80 per million tokens |
| Output Cost | $4 per million tokens |
| Speed | Fastest in the Claude family |
| Best For | Autocomplete, simple scripts, quick Q&A, tab completion |
Strengths for Vibe Coding
- Near-instant responses: Perfect for the fast feedback loops vibe coding needs
- Extremely cheap: At under $1/million input tokens, you can send thousands of prompts
- Great for autocomplete: Powers tab completion in Cursor and other IDEs — fills in code as you type
- Good for simple tasks: Generating utility functions, writing tests, formatting data, simple HTML/CSS
Limitations
- Struggles with complexity: Multi-file edits, complex architecture decisions, and subtle bugs can trip it up
- Shorter output: 8K max output means it can't generate as much code per response
- Less reliable instruction following: May miss details in complex multi-part prompts
- Not ideal for main coding agent: Better as an assistant (autocomplete) than the primary coding model
Best Use Pattern
The combo strategy: Many vibe coders use Haiku for autocomplete/tab completion (fast, cheap) and Sonnet or Opus for the main chat-based coding (smarter). This gives you speed where speed matters and intelligence where intelligence matters.
Example Prompt
Quick task prompt (perfect for Haiku)
Write a function that takes an array of objects with
name and score properties, and returns the top 3
highest scorers sorted by score descending.