Claude Model Comparison — Opus, Sonnet, or Haiku?
You've signed up for a Pro plan and now you're wondering: "What are Opus, Sonnet, and Haiku? Which one should I use?"
This article answers that question. Choosing a plan is covered separately in Claude Pricing Plans Compared. Here, we focus on how to choose the right model for your day-to-day tasks once you're on Pro or higher.
Who this article is for: This is a full comparison of all models available on Pro, Max, Team, and Enterprise plans. Free plan users have access to Sonnet and Haiku only. If you're still deciding which plan to get, see Claude Pricing Plans Compared first.
Quick Model Comparison
Claude currently has three models. They're all the same AI — "Claude" — but they differ in capability, speed, and how much of your usage quota they consume. Think of it like a chef who can cook an elaborate multi-course meal, a reliable everyday lunch special, or a quick snack — same skills, different modes.
| Model | Description | Capability | Speed | Usage Cost | Best For |
|---|---|---|---|---|---|
| Opus | Maximum power — thinks deeply | Highest | Somewhat slow | High | Complex analysis, document review, advanced reasoning |
| Sonnet | Balanced — the everyday all-rounder | High | Fast | Standard | General work, writing, research |
| Haiku | Fastest and lightest | Standard | Fastest | Low | Translation, simple questions, high-volume tasks |
Common misconception: "Why not just always use Opus?" Because Opus consumes more of your usage quota — you'll hit your daily message limit faster. Matching the model to the task lets you work comfortably without constantly running into limits.
Opus — Deep Thinking, Maximum Performance
Claude Opus is the most capable model currently available. It approaches complex problems from multiple angles before responding.
What Opus Does Best
- Complex analysis and reasoning — Untangling problems with many interacting variables
- High-quality writing — Documents that demand logical structure and polished expression
- Precise review of long documents — Situations where subtle nuance matters
- Expert-level judgment — Providing careful, considered opinions on ambiguous situations
When to Use Opus — Concrete Examples
Reviewing contracts and legal documents "Read this 30-page service agreement and identify every clause that poses a risk to us." When careful contextual reading is essential, Opus's precision shines.
Complex business strategy analysis "Compare the strategies of competitors A, B, and C, then recommend which market segment we should enter." Tasks requiring multi-step reasoning.
High-stakes writing Executive reports, important client proposals — documents where quality cannot be compromised.
Things to Keep in Mind
- Responses take longer: Compared to Sonnet, Opus takes more time — sometimes several seconds to a minute for complex questions
- Higher usage cost: The same conversation uses more of your quota with Opus than with Sonnet. You'll reach limits sooner
- Overkill for simple tasks: For "summarize this paragraph" or "translate this to French," Opus offers little advantage over Sonnet or Haiku
Opus is only available on Pro plans and above — it's not on the Free plan. Because it consumes more quota, using Opus all day will hit your limit quickly. Save it for your most important tasks.
Sonnet — The Balanced Everyday Model
Claude Sonnet offers the best balance of capability and speed. "When in doubt, start with Sonnet" is the golden rule for getting the most out of Claude.
What Sonnet Does Best
- Everyday document creation — Emails, reports, meeting notes
- Organizing and summarizing information — Condensing long documents or multiple sources
- Brainstorming and ideation — Generating a wide range of ideas quickly
- Research assistance — Organizing information on a specific topic
- Light code help — Basic programming assistance and explanations
When to Use Sonnet — Concrete Examples
Writing meeting minutes "Turn these meeting notes into formal minutes. Clearly list decisions made and action items." For tasks you do every day, Sonnet is more than enough.
Drafting business emails "Write a polite rejection to a vendor — keep the relationship intact." Standard business correspondence like this is perfect for Sonnet.
Summarizing reports "Condense this 10-page report into a one-page executive summary for leadership." A classic Sonnet task.
Why "Start with Sonnet"
On many benchmarks, Sonnet scores nearly as well as Opus — in everyday work, the difference is barely noticeable. For certain highly demanding tasks like PhD-level reasoning, Opus does pull ahead. But since Sonnet uses less quota, the smart approach is to start with Sonnet and only switch to Opus when you feel you need more depth.
Haiku — Fast, Light, and Ready
Claude Haiku is the fastest and most quota-efficient model. Like the poetry form it's named after — brief, swift, to the point.
What Haiku Does Best
- Translation — Converting text into another language or register
- Simple questions — Quick lookups, term definitions
- Basic text transformations — Bullet points, format conversions
- High-volume repetitive tasks — Handling many similar requests in sequence
- Quota-saving fallback — When you're approaching your Sonnet or Opus limit
When to Use Haiku — Concrete Examples
Translating emails "Translate this English email into French." Simple translation is fast and accurate with Haiku.
Checking word meanings "What does 'due diligence' mean in a business context?" One-question, one-answer exchanges.
Converting document formats "Turn this bullet list into a table." Mechanical formatting tasks where Haiku excels.
Common misconception: "Haiku is lower quality, so I'll skip it." For straightforward tasks, Haiku produces results nearly identical to Sonnet. And since it uses far less quota, switching to Haiku when your limit is running low lets you keep working.
Task-Based Model Recommendations
Quick guide for when you're not sure which to pick.
| Task | Recommended Model | Why |
|---|---|---|
| Reviewing contracts and legal documents | Opus | Requires precision to catch subtle nuances |
| Writing important proposals or plans | Opus | When logical quality and polished expression matter |
| Complex data analysis and interpretation | Opus | Needs multi-angle reasoning |
| Everyday emails and documents | Sonnet | Best balance of speed and quality |
| Writing meeting minutes | Sonnet | Great at structure and summarization |
| Market research and information gathering | Sonnet | Broad knowledge and organization |
| Planning presentation structures | Sonnet | Strong at ideation and structuring |
| Translating to/from other languages | Haiku | Sufficient accuracy at high speed |
| Looking up word or term meanings | Haiku | Fast, accurate quick answers |
| Converting large volumes of short text | Haiku | Low quota cost suits high-volume work |
| Continuing work when approaching limits | Haiku | Low quota cost keeps you going |
How to Switch Models
Selecting a Model in claude.ai
In the claude.ai chat interface, click the model name next to the send button to switch models. Note: changing the model starts a new chat — your previous conversation stays as a separate chat.
The dropdown shows all available models with a brief description next to each name.
About the "Auto" setting: If you see an "Auto" option in the model selector, Claude will automatically pick the best model based on task complexity. It's a convenient default, but it makes your quota usage harder to predict — if you want to stay in control of how fast you burn through your limits, set the model manually.
Free Plan Restrictions
Free plan users can only access Haiku and Sonnet. To use Opus, you'll need to upgrade to Pro or higher.
Model Selection Tips
- Start with Sonnet — Try Sonnet first. Only switch to Opus if you feel you need more depth
- Use Haiku for repetitive tasks — High-volume translation, conversion, or similar work? Haiku saves your quota
- Finish with Opus — Use Opus for final reviews and high-stakes outputs where quality is critical
Bonus: Mythos — A Model for Security Research
In April 2026, Anthropic announced a new model called Claude Mythos Preview. Unlike Opus, Sonnet, and Haiku, Mythos occupies a very different niche.
What Is Claude Mythos?
Mythos is a model with exceptional capability in computer security — specifically discovering and analyzing vulnerabilities (security flaws in software). According to Anthropic's announcement, Mythos autonomously discovered numerous zero-day vulnerabilities (previously unknown flaws) in major operating systems and browsers in just a few weeks.
Project Glasswing
Mythos is being made available through an initiative called Project Glasswing. Twelve organizations participate — including Anthropic, Amazon Web Services (AWS), Apple, Broadcom, Cisco, CrowdStrike, Google, JPMorganChase, the Linux Foundation, Microsoft, NVIDIA, and Palo Alto Networks — for the purpose of defensive security (finding and fixing vulnerabilities in your own systems before attackers do).
See the Anthropic Project Glasswing page for details.
Not Available to the Public
Mythos is not available to general users. Anthropic is not offering self-serve access — it's running as an invite-only limited preview.
Anthropic has said they aim to make it more broadly available once they're confident in its safety, but as of April 2026, it is not accessible to regular users.
The models available to you on claude.ai and the mobile app remain Opus, Sonnet, and Haiku. Think of Mythos as interesting background knowledge — it doesn't change how you use Claude day-to-day.
Frequently Asked Questions
Does using Opus drain my usage limit faster?
Yes. Opus consumes more quota than Sonnet, so you'll hit your daily limit sooner with the same number of messages. Anthropic hasn't published exact multipliers, but in practice Opus feels noticeably faster at reaching limits.
Three ways to manage this:
- Reserve Opus for important tasks — Use Sonnet or Haiku for everyday work
- Switch to Haiku as you approach your limit — Stay productive without waiting for the reset
- Consider upgrading to Max — If you frequently hit limits, the Max plan offers significantly more quota
Is it fine to leave it on "Auto"?
The Auto setting removes the guesswork by letting Claude choose the model. The downside is that it's harder to predict your quota usage — Opus may get selected more often than you'd like, and you'll hit limits without realizing why.
Recommended approach: Manually select Sonnet as your default. Only switch to Opus when you feel the response needs more depth. This keeps your quota usage predictable.
How different are Sonnet and Haiku?
For simple, everyday tasks — translation, summarization, text conversion — the difference is barely noticeable. For complex reasoning or high-quality writing, Sonnet clearly produces better results.
When in doubt, start with Sonnet. If you need faster responses or want to conserve quota, try Haiku.
Should I care about version numbers like 4.6 or 4.5?
If you're using claude.ai as a regular user, no — you don't need to think about version numbers. Claude always uses the latest version automatically. Just remember the three names: Opus, Sonnet, Haiku.
Version numbers (4.6, 4.5, etc.) are relevant for developers calling Claude via the API, where pinning a specific version is sometimes necessary.
Can I switch models on the mobile app?
Yes. The Claude iOS and Android apps support model switching. Tap the model name at the top of the chat screen to open the selector.
Is Haiku available on the Free plan?
Yes. Both Haiku and Sonnet are available on the Free plan. Opus requires Pro or higher.
Next Steps
- Claude Pricing Plans Compared — Deciding which plan to subscribe to
- How to Use Claude Web (claude.ai) — Learn the basics of the browser interface