The short answer
Anthropic’s current lineup has three everyday tiers. Opus 5.5 is for long-running, complex work such as agentic coding and heavy knowledge work. Sonnet 5.5 is described as the best mix of speed and intelligence, and it is the right default for most business tasks. Haiku 5.5 is the fastest, aimed at high-volume jobs like sorting, extraction and routing. In the Claude app, start with the default, move up to Opus when the answer is not good enough, and use Haiku through tools that process lots of items.
- Opus 5.5: the most capable of the three, best for complex, long-running work.
- Sonnet 5.5: fast and strong, the sensible default for everyday business work.
- Haiku 5.5: the fastest, for high-volume, simple jobs.
- Anthropic also has a higher tier above Opus, Fable, for the most demanding reasoning.
Claude Opus 5.5 vs Claude Sonnet 5.5 at a glance
| What matters | Claude Opus 5.5 | Claude Sonnet 5.5 |
|---|---|---|
| Anthropic’s description | Long-running agentic coding and knowledge work | The best combination of speed and intelligence |
| Speed | Moderate | Fast |
| Best business use | Hard analysis, big documents, complex builds | Daily writing, summaries, emails, spreadsheets |
| Main downside | Slower and costlier to run | May fall short on the hardest reasoning |
The three tiers in plain English
Think of Claude models like staff grades. Haiku is the quick junior who clears the pile. Sonnet is the experienced all-rounder you use most days. Opus is the senior specialist you bring in for the problem that has beaten the others. All three currently carry the 5.5 version number and a 1 million token context window. The newest versions are only weeks old, so expect Anthropic to keep refreshing them and older names to disappear over time. Sources: Claude models overview
When Opus 5.5 is worth it
Anthropic positions Opus 5.5 for long-running agentic coding and knowledge work, and said at launch it performs at about the level of its previous top model on most work at roughly 40 percent lower running cost than Opus 5. Reach for it on a complex contract review, a big analysis, or a multi-step build where Sonnet’s answer was not good enough. Sources: Introducing Claude Opus 5.5, Claude models overview
Why Sonnet 5.5 is the default
Anthropic describes Sonnet 5.5 as the best combination of speed and intelligence. For emails, summaries, proposals, meeting notes and spreadsheet questions, the extra capability of Opus rarely changes the result, while the speed difference is noticeable. If you only remember one rule, use Sonnet and escalate only when you have a reason. The cost of a model is also the time you wait, and for daily work a quick good answer beats a slow marginally better one. Sources: Claude models overview
What Haiku 5.5 is for
Haiku is the fastest and cheapest model, built for high-volume, latency-sensitive tasks such as classification, extraction and routing. Owners rarely pick it by hand in the chat app. It matters when a developer builds a tool that has to sort a thousand enquiries or pull fields from invoices at low cost. If you are not building or buying an automation, you can safely ignore Haiku and still get full value from Claude. Sources: Claude models overview
What about Fable?
Anthropic’s documentation lists a tier above Opus called Fable 5.1, for demanding reasoning and long-horizon agentic work. It costs more and runs slower. Most small and mid-sized businesses will not need it, and plan inclusion varies, so check the pricing page. Anthropic describes it as for demanding reasoning and long-horizon agentic work, so it is a specialist tool rather than an upgrade for everyone. Run the same test you would for Opus before paying more. Sources: Claude models overview, Claude pricing
A simple rule of thumb
Start on Sonnet. If the answer is shallow, wrong or misses nuance, rerun the same prompt on Opus and compare. If you are building an automation that handles volume, test Haiku first and step up only if accuracy drops. Keep notes on which model handled which task, and revisit them when Anthropic releases new versions. The model that gets the job right first time is the cheap one, whatever its list price.
Questions people ask
Which Claude model is best?
Opus 5.5 is the most capable of the three, but Sonnet 5.5 is the better default because it is faster and good enough for most business tasks.
Is Haiku good enough for business?
For simple, high-volume jobs, yes. For nuanced writing or analysis, use Sonnet or Opus.
Do model names change?
Yes. Anthropic releases new versions regularly, so check the models overview for the current lineup.
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