- What is Claude Haiku 5.5?
- Who can use Haiku 5.5, and where
- How to switch to Claude Haiku 5.5
- When to pick Haiku over Sonnet or Opus
- Prompts that suit Haiku 5.5
- Tips for getting better answers from Haiku
- Using Haiku 5.5 in Claude Code
- Mistakes to avoid with a fast model
- Tools that work with Claude Haiku 5.5
- Frequently asked questions
Claude Haiku 5.5 is Anthropic's newest small model, released on 7 October, and its fastest model yet. Free, Pro, Max, Team and Enterprise users can pick it from the model menu on Claude.ai, on the web, iOS and Android, and it's also in Claude Code. Use it for quick, repetitive jobs like sorting messages, summarising notes, pulling details out of documents and drafting short replies, and switch to Sonnet 5.5 or Opus 5.5 for bigger, harder work.
Anthropic released Claude Haiku 5.5 on 7 October. It's the small, quick member of the Claude family, and it's now open to everyone on Claude.ai, including the Free plan.
Most guides to new models focus on benchmarks. This one's about when to reach for Haiku 5.5 in a small business, how to switch to it, and the prompts that suit it best. Every fact comes from Anthropic's own announcement, its Haiku page and the Claude developer docs.
What is Claude Haiku 5.5?
Anthropic builds Claude in three main sizes: Haiku, Sonnet and Opus. Haiku is the lightest and quickest. Anthropic calls Haiku 5.5 the most capable small model it has released, and its docs list it as the fastest model in the current line-up.
It's built for high-volume, quick-turnaround work. Anthropic's examples include classification, routing, extraction, summaries and acting as a helper, or subagent, for bigger models. It reads text and images and replies in text.
What's new compared with Haiku 4.5
- An effort setting. Haiku 5.5 is the first Haiku with adjustable effort, with levels from Low through Med, High and Xhigh up to Max. Higher effort means more thinking on harder questions.
- Adaptive thinking. It decides for itself how much to think, steered by that effort level.
- Much stronger results. Anthropic reports big jumps over Haiku 4.5 on its published tests, especially on office tasks and computer use.
Who can use Haiku 5.5, and where
| Where | Who |
|---|---|
| Claude.ai on web, iOS and Android | Free, Pro, Max, Team and Enterprise users |
| Claude Code | Available |
| Claude API | Developers, as claude-haiku-5-5 |
| Amazon Bedrock, Google Cloud, Microsoft Foundry | Available |
How to switch to Claude Haiku 5.5
- Open Claude.ai in your browser or the Claude app on your phone and sign in.
- Start a new chat and open the model menu.
- Choose Haiku 5.5.
- Ask your question or paste in the text you want it to work on.
- When the job gets complex, like a long strategy document or a tricky analysis, switch the chat back to Sonnet 5.5 or Opus 5.5.
In Claude Code, Haiku 5.5 is also on the list, which makes it a good pick for small, focused edits and quick tool use. Anthropic is clear that Sonnet 5.5 and Opus 5.5 are still the better choices for complex coding projects.
When to pick Haiku over Sonnet or Opus
Think of Haiku as the fast assistant who clears the small stuff. Here's how I'd split the work in a small business.
| Job | Best fit |
|---|---|
| Sorting and tagging customer messages | Haiku 5.5 |
| Summarising meeting notes or long emails | Haiku 5.5 |
| Pulling names, dates and order details out of documents | Haiku 5.5 |
| Quick replies for live chat or support | Haiku 5.5 |
| Long-form blog posts in your voice | Sonnet 5.5 |
| Business strategy, complex analysis, big coding jobs | Opus 5.5 |
If you write a lot, my guide to the best Claude model for writing goes deeper on which model suits which kind of copy, and how Claude's usage limits work explains what happens when you hit them.
Prompts that suit Haiku 5.5
Haiku does best with clear, focused instructions and a defined output. Give it the format you want and let it get on with it.
Copy this prompt
Sort these customer messages into these groups: question about an order, complaint, sales enquiry, other.
For each one, give me the group, a one-line summary, and an urgency rating from low to high.
Messages: [paste messages].
Copy this prompt
Summarise these meeting notes in five bullet points.
Then list every action, who owns it and the date it's due, in a simple table.
Notes: [paste notes].
Copy this prompt
Pull the following details out of each document I paste: customer name, company, date, what they ordered, and any special request.
Return them as a table with one row per document. If a detail is missing, write not given.
Documents: [paste text].
Copy this prompt
You answer questions for [business name], which sells [what you sell].
Write a short, friendly reply to this customer message in plain English, in three sentences or fewer, and suggest one next step.
Customer message: [paste message].Work with meWant AI doing the heavy lifting in your marketing?
I build the systems that handle the boring 80 percent, so you get your week back. Done properly, with the human kept in.
Copy this prompt
Rewrite these product descriptions so each one is under fifty words, starts with the main benefit and ends with a short call to action.
Keep my tone: [describe your tone].
Descriptions: [paste them].
Tips for getting better answers from Haiku
- Batch similar jobs. Haiku is quick, so paste in a batch of messages or descriptions at once and ask for a table back.
- Give it the format. A named list of columns or groups gets you tidier output than an open question.
- Use Projects for repeat work. Put your tone notes and product details in a project so every Haiku chat starts with the right background. My guide to Claude Projects shows you how.
- Know when to step up. If an answer feels thin on a hard question, raise the effort or switch to Sonnet or Opus.
Using Haiku 5.5 in Claude Code
Anthropic's Haiku page says Haiku 5.5 handles focused coding and multi-step tool use, like direct edits and small, specific changes. That makes it a handy pick for the little jobs on a website or internal tool: fixing a typo across a few files, renaming something, tidying a short script or adding a simple field to a form.
It also works as a helper alongside Opus 5.5 and Sonnet 5.5. A bigger model can plan the work and hand the narrow, repetitive parts to Haiku, which keeps things moving quickly. For a full build or a tricky bug, start with Sonnet 5.5 or Opus 5.5.
Copy this prompt
Make this one small change and nothing else: [describe the change].
Files to touch: [list files].
Show me the exact lines you changed and tell me how to check it worked.
Mistakes to avoid with a fast model
- Asking it for strategy. Haiku is quick, but a business plan or a complex analysis deserves Sonnet or Opus.
- Vague requests. A loose question gets a loose answer. Name the groups, columns or length you want.
- Skipping the check. Spot check a few rows when it sorts or extracts a big batch, especially before anything goes to a customer.
- Forgetting the effort setting. If you're getting thin answers on harder questions, raise the effort before you give up on it.
Anthropic's Haiku page also lists computer use for repetitive tasks like form filling and data entry, and latency-sensitive uses like chat, voice agents, live support and in-app assistants. Those are the jobs where speed matters more than depth, which is exactly where Haiku shines.
Tools that work with Claude Haiku 5.5
Haiku 5.5 shows up in more places than the Claude app. These are the main ones, plus tools small teams often pair with it:
- Claude Code, where Haiku 5.5 handles small, specific edits.
- Amazon Bedrock, Google Cloud and Microsoft Foundry, for teams that build on those platforms.
- Zapier or Make, which teams often use to pass messages to Claude through the API and back into their other apps.
- Google Sheets or Airtable, for storing the tables Haiku produces when it sorts or extracts details.
- Intercom or Zendesk, where quick support replies drafted by a fast model fit naturally.
If you'd like help working out which Claude model fits each job in your business, you can work with me here.
Frequently asked questions
Is Claude Haiku 5.5 free?
Yes, you can use it on the Free plan. Anthropic says Free, Pro, Max, Team and Enterprise users can select Haiku 5.5 on Claude.ai, on the web, iOS and Android.
When was Claude Haiku 5.5 released?
Anthropic released it on 7 October.
Is Haiku 5.5 better than Sonnet 5.5?
Not for complex work. Haiku 5.5 is quicker and built for high-volume, focused jobs, while Anthropic says Sonnet 5.5 and Opus 5.5 remain the better choices for complex coding and agent work.
What is the effort setting in Haiku 5.5?
It's a control over how much the model thinks. Haiku 5.5 is the first Haiku with it, with levels from Low through to Max. Higher effort helps on harder questions.
Can I use Haiku 5.5 in Claude Code?
Yes. Anthropic says Claude Haiku 5.5 is available in Claude Code, where it suits focused coding and small, specific changes.
