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Chat model · Anthropic

Claude Opus 4.5

Included in Pro · came out November 2025

For long reports and formal letters that need a steady hand

Claude Opus 4.5 is an earlier version of Opus, the most careful size of Anthropic's Claude. It suits you if you want thorough answers on long jobs and don't need the web.

Chat with Claude Opus 4.5

Claude Opus 4.5 in numbers

What it knows about

Up to May 2025

It learned from information up to May 2025. It can't search the web, so for recent news or prices pick a model that can.

What you can give it

  • Your wordsYes
  • PhotosYes
  • PDFs and filesYes
  • The webNot this one

Real answers

See how Claude Opus 4.5 answers

We asked it the same everyday questions as every other model in chatmodel, one try each. This is exactly what came back.

My neighbour watered my plants for two weeks while I was away. Write a short, warm thank-you note I can leave with a small gift. Keep it under 80 words.

Dear [Neighbor's name],

Thank you so much for looking after my plants while I was away! It was such a relief knowing they were in good hands, and I came home to find them thriving thanks to your care.

Your kindness and thoughtfulness mean the world to me. I'm so lucky to have you as a neighbor.

Please enjoy this small token of my appreciation—you truly made my trip worry-free!

With gratitude, [Your name]

Answered in about 4 seconds · 74 words

Ask it yourself

The Claude family in chatmodel

The newest is Claude Fable 5.1. Ordered by release date.

  1. September 2025Claude Sonnet 4.5
  2. October 2025Claude Haiku 4.5
  3. November 2025Claude Opus 4.5You're here
  4. February 2026Claude Opus 4.6
  5. February 2026Claude Sonnet 4.6
  6. April 2026Claude Opus 4.7
  7. May 2026Claude Opus 4.8

What it's good for

Try it with one of these

Press “Try this” and chatmodel opens with Claude Opus 4.5 selected and the message already written. Change any word you like.

Write a reference letter

“Help me write a reference letter for Maria, who worked in my shop for three years. She was reliable, great with older customers and handled the till. Keep it warm but professional, one page at most.”

Try this

Explain my pension statement

“I'm going to upload my yearly pension statement. Tell me in plain words what I have saved, what I might get when I retire, and any terms I should ask my provider to explain.”

Try this

Plan a kitchen renovation

“We want to redo our kitchen in the spring. Put the jobs in the right order, from measuring to the final paint, and tell me which ones usually cause delays so I can plan around them.”

Try this

Make sense of a bill

“I'll send a photo of my energy bill. Explain each charge in plain words and tell me what I could ask the supplier to lower it.”

Try this

In plain words

Claude Opus 4.5 is a chat assistant from Anthropic. Opus is the most careful size of Claude, and 4.5 is the first of the Opus 4 versions you can pick in chatmodel.

It thinks before it answers, reads PDFs and understands photos. It doesn’t search the web, so it works from what it already knows and what you give it.

How to get the most out of it

  1. Upload the whole document. It’s patient with long texts, so there’s no need to copy out the important parts.
  2. Say what you’ll do with the answer. “I need to decide by Friday” or “I’m going to phone them” changes what it focuses on.
  3. Ask for a checklist at the end. For projects and paperwork, a short list of next steps is easy to act on.
  4. Give it the tone for letters. “Formal, but not cold” works better than no instruction.

How it compares with its siblings

It’s the oldest Opus here. Claude Opus 4.6 and Claude Opus 4.7 came next, and Claude Opus 4.8 added web search. Claude Opus 5 came after all of them. For quicker answers in the same style, try Claude Sonnet 4.5, and for the most demanding jobs, Claude Fable 5.

When to pick another model

If you need recent information, choose a model that can search the web, like GPT 5.5. To see how Claude and ChatGPT differ, read ChatGPT vs Claude. For documents, the PDF chat tool gets you started in one click.

Other models worth a look

Claude Opus 4.6

Anthropic

Read the guide

Claude Opus 5

Anthropic

Read the guide

Claude Sonnet 4.5

Anthropic

Read the guide

Frequently asked questions

Is Claude Opus 4.5 still worth using?

Yes, for long and careful jobs it remains a solid choice. If you want a newer Opus or answers that use the web, pick Claude Opus 5 instead.

Can it search the web?

No. In chatmodel it answers from what it already knows and from the files you share.

Can it read PDFs and photos?

Yes. You can upload documents and photos and ask questions about them.

What's the difference between Opus and Sonnet?

Both are Claude, made by Anthropic. Opus is the bigger, more careful size. Sonnet tends to be quicker for everyday tasks.

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