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o3-pro

Claude Sonnet 4.5

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The basics

Released

Jun 10, 2025
Sep 29, 2025

What it does

Text and chat: Writes, answers questions and holds a conversation.Thinks first: Can reason step by step before it answers: slower, but better at maths, code and tricky questions.Sees images: Understands pictures, screenshots and charts you share with it.
Text and chat: Writes, answers questions and holds a conversation.Code: Writes, explains and fixes code.Thinks first: Can reason step by step before it answers: slower, but better at maths, code and tricky questions.Sees images: Understands pictures, screenshots and charts you share with it.Reads files: Reads documents such as PDFs.

Knowledge cutoff

The latest events it learned about

May 2024
July 2025More recent

Download

No: it runs on the maker's servers
No: it runs on the maker's servers

Where to use it

OpenAI's app: ChatGPT ↗
Anthropic's app: Claude ↗Also for developers, through an API

Price and limits, for developers

Input

Per million tokens

$20.00
$3.00Cheaper

Output

Per million tokens

$80.00
$15.00Cheaper

Cached input

Per million tokens

Not listed
$0.30

Context window

How much it takes in at once

200K tokens about 150,000 words
200K tokens about 150,000 words

Longest answer

100K tokens about 75,000 wordsLonger
64K tokens about 48,000 words

How they score

Combined test score

Epoch Capabilities Index · Epoch AI

147#79 of 237
148#78 of 237

Too close to call: o3-pro and Claude Sonnet 4.5 are within the margin of error.

Chat answers, by people's votes

LMArena text, adjusted for style · LMArena

Not ranked
1,456#58 of 86

Only Claude Sonnet 4.5 is in this ranking, which lists the most-voted models.

Green marks the better of the two on each row, red the other. Rows where one side isn't listed, or where the gap is too close to call, stay plain.

Popular comparisons

Not sure where to start? Which AI should I use? gives a pick for what you want to do. How to read AI rankings explains the numbers.

Rankings from LMArena and Epoch AI, both CC BY 4.0, updated . Developer prices, context windows and knowledge cutoffs from the labs' own listings on models.dev and from OpenRouter. The app links go to each maker's own app when no source says exactly where the model is available.

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