Claude Models
Claude Models
Claude models are the underlying AI language models made by Anthropic that power Claude Code, Claude.ai, and the broader Claude API platform. They range from smaller, faster models optimised for quick responses to larger, more capable models designed for complex reasoning and deep code analysis.
As of early 2026, the Claude model family comprises three distinct tiers, each suited to a different class of task.
Model Tiers
Claude Haiku
Haiku is the smallest and fastest model in the Claude family. It is designed for high-throughput, low-latency tasks where speed and cost efficiency matter most.
Best used for:
- Simple code completions and short rewrites
- Quick factual lookups and summarisation
- High-volume, routine tasks where response time is critical
- Drafting and iteration where you need rapid feedback
Claude Sonnet
Sonnet sits in the middle of the model range, offering a strong balance between speed and capability. It handles a wide variety of tasks well and is the default choice for most day-to-day development work.
Best used for:
- Feature research and planning
- Writing and reviewing code across a full feature
- Answering technical questions that require moderate reasoning
- Tasks where you need solid quality without the latency of a larger model
Claude Opus
Opus is the largest and most capable model in the Claude family. It excels at tasks that demand deep reasoning, nuanced analysis, and careful multi-step problem solving.
Best used for:
- Complex architectural decisions and design reviews
- Pull request reviews that require subtle judgement about code quality
- Debugging difficult or ambiguous issues
- Tasks where getting the answer right matters more than getting it fast
Choosing the Right Model
When using Claude Code or dispatching agents, you can often specify which model to use. The general rule is straightforward:
| Task complexity | Recommended model | Why |
|---|---|---|
| Simple, repetitive | Haiku | Fastest and cheapest |
| Moderate, everyday | Sonnet | Good balance of quality and speed |
| Complex, high-stakes | Opus | Best reasoning and analysis |
In many agent workflows, the model choice is made automatically based on the complexity of the task at hand. Simpler sub-tasks within a larger workflow may use Haiku, whilst the planning and decision-making steps use Sonnet or Opus.
About Anthropic
All Claude models are developed by Anthropic, an AI safety company focused on building reliable, interpretable, and steerable AI systems. Anthropic publishes model documentation and usage guidance on the Claude documentation site.