Claude Models Explained: Opus, Sonnet & Haiku

Anthropic organizes Claude’s AI models into three tiers: Opus, Sonnet, and Haiku. Each tier is designed for different use cases — from complex reasoning and long coding tasks to fast everyday responses. This guide explains what each model does, who it is for, and how app and API users access them differently.

Note: Model names, capabilities, and pricing change over time. The information in this guide reflects officially published Anthropic data at the time of writing. Check Anthropic’s model overview for the current lineup.

The Claude Model Family

Claude models are grouped into three named tiers that reflect their position on the speed-vs-capability spectrum:

• Opus — the most capable tier. Designed for the hardest problems: complex reasoning, long-context analysis, and agentic coding tasks.
• Sonnet — the balanced tier. Strong intelligence with faster responses. Good for most professional and creative tasks.
• Haiku — the fastest tier. Near-frontier intelligence at the highest speed. Good for simple tasks, quick lookups, and cost-sensitive applications.

Each generation of Claude updates the models within these tiers. The current generation is Claude 4.x, with Opus 4.8, Sonnet 4.6, and Haiku 4.5 as the latest tier models. In June 2026, Anthropic added a new tier above Opus: Claude Fable 5, its most capable widely released model.

Claude Models: Current Lineup at a Glance

API pricing and model specs are verified from Anthropic’s official model overview at time of writing. Check the official page for current pricing — it can change.

Claude Fable 5 and Claude Mythos 5: The New Top Tier

On June 9, 2026, Anthropic launched Claude Fable 5 (claude-fable-5) — its most capable widely released model, positioned above the Opus tier. Fable 5 is priced at $10 input / $50 output per MTok, has a 1M token context window with 128k max output, and uses adaptive thinking (always on; it does not support manual extended thinking). It is generally available via the Claude API and major cloud platforms. Through June 22, 2026 it is also included on Pro, Max, Team, and seat-based Enterprise plans at no extra cost; from June 23, Anthropic says continued subscription use requires usage credits unless capacity allows standard access to be restored — check claude.com/pricing for current availability.

Claude Mythos 5 (claude-mythos-5) is the same underlying model with some safeguards lifted. It is not a public self-serve model — access is limited to approved customers in Anthropic’s Project Glasswing trusted-access program. When Fable 5’s safety classifiers trigger (in under 5% of sessions, per Anthropic), the request is routed to Claude Opus 4.8 instead.

Claude Opus 4.8: Best for Complex Tasks

Claude Opus 4.8 is Anthropic’s most capable Opus-tier model — and was the overall flagship until Claude Fable 5 launched in June 2026. Anthropic describes it as delivering a “step-change improvement in agentic coding” compared to the previous Opus 4.6 generation. It also serves as the fallback model when Fable 5’s safeguards route a request away, and it costs half as much as Fable 5 per token.

Use Claude Opus 4.8 for:

• Complex, multi-step reasoning problems
• Agentic coding — tasks where Claude takes multiple actions, runs code, and iterates
• Long document analysis — with a 1M token context window, it can process entire books or codebases
• Research synthesis across large amounts of material
• Situations where accuracy and thoroughness matter more than speed

For a full deep-dive including comparison with Opus 4.7, effort control, and API usage examples, see the Claude Opus 4.8 guide.

Opus 4.8 is slower and more expensive to run via the API than Sonnet or Haiku. For most everyday tasks, Sonnet 4.6 is a more efficient choice. Opus is the right pick when you genuinely need the highest capability.

Claude Sonnet 4.6: Best Balance of Speed and Intelligence

Claude Sonnet 4.6 is Anthropic’s recommended model for most everyday use cases. It delivers strong intelligence at faster response times than Opus, making it the practical choice for most professional tasks.

Use Claude Sonnet 4.6 for:

• Writing, editing, and summarization
• Coding tasks and code review
• Research and analysis
• Customer-facing applications where response speed matters
• Most general-purpose work where Opus would be overkill

Sonnet 4.6 also supports a 1M token context window, meaning it handles long documents just as well as Opus — often the only reason to upgrade to Opus is for the most demanding reasoning or agentic tasks.

Claude Haiku 4.5: Fastest Responses

Claude Haiku 4.5 is the fastest Claude model with near-frontier intelligence. It is designed for applications where speed and cost efficiency are more important than maximum capability.

Use Claude Haiku 4.5 for:

• Quick lookups and simple Q&A
• High-volume applications where API cost per request matters
• Real-time or near-real-time response applications
• Lightweight summarization or classification tasks
• Situations where latency is critical and the task does not require deep reasoning

Haiku’s 200k token context window is still generous for most tasks. Its API cost ($1 input / $5 output per MTok) makes it significantly more affordable than Sonnet or Opus at scale.

App Users vs API Users: Different Access Paths

Claude is available in two ways, and each has its own pricing structure:

Claude App (Consumer Plans)

If you use Claude at claude.com, the Claude mobile app, or the Claude desktop app, you are on a consumer plan:

• Free plan: $0 — access to Claude with usage limits
• Pro plan: $17/mo (annual) or $20/mo monthly — more usage, access to multiple models
• Max plan: from $100/mo — 5x or 20x Pro usage

On consumer plans, Anthropic determines which models are available at which tier. You do not select a model by API ID — you choose it in the interface when it is offered.

Claude API (Developer Plans)

Developers who build applications using the Anthropic API pay per token (input and output) based on which model they call. API pricing uses the model IDs in the table above.

• API users select models by ID: claude-opus-4-8, claude-sonnet-4-6, claude-haiku-4-5
• You pay per use — no monthly subscription, though Anthropic may require adding API credits
• API pricing is separate from and not interchangeable with consumer plan pricing

See the Claude API Key guide for getting started with the API.

Which Claude Model Should You Use?

Most Claude app users on a paid plan should use Sonnet 4.6 as their default and upgrade to Opus 4.8 only for tasks where they notice Sonnet’s reasoning falling short. For quick tasks, Haiku 4.5 is the fastest option.

• Default choice for most users: Claude Sonnet 4.6
• Complex research, large codebases, or agentic coding: Claude Opus 4.8
• Quick tasks, high-volume, or cost-sensitive API use: Claude Haiku 4.5
• Free plan users: Anthropic determines model access — you may get access to a Haiku or Sonnet tier model

If you are uncertain, start with Sonnet 4.6. You can always switch to Opus for specific tasks when you need more capability.

Comparing Claude to other AI tools? See the Claude vs GPT-4o comparison for a task-based guide, or the Claude vs ChatGPT guide for a broader product comparison.

To help choose the right model for your use case, try the Claude Model Selector tool. For API users, the Claude API Cost Estimator helps project costs before scaling. For tasks with repeated context, see the Claude Prompt Caching Guide.