Claude Sonnet 4.5

4.5 · Family: Claude

Anthropic's Claude family AI model focused on coding, agentic tasks and computer use, with a 200K-token context window.

✓ Active✓ Public accessLLMMultimodal📁 Claude

Context window

200K

tokens

Max output

64,000

tokens

Release date

29 September 2025

🏢AnthropicProducer

Access:APIHostedDeployment:☁ Cloud

Overview

Claude Sonnet 4.5 is a Claude family language model released by Anthropic on September 29, 2025. Anthropic positions it as a leading model for coding, building complex agents, and computer use, with substantial gains in reasoning and math compared to Sonnet 4. The model accepts text and image input and produces text output, including code. The default context window is 200,000 tokens and maximum output is 64,000 tokens. The API identifier is claude-sonnet-4-5 (snapshot claude-sonnet-4-5-20250929). It is available via the Claude API, AWS Bedrock, Google Vertex AI, and Microsoft Foundry. Pricing is USD 3 per 1M input tokens and USD 15 per 1M output tokens. Sonnet 4.5 supports extended thinking. Anthropic deployed the model under AI Safety Level 3 (ASL-3) safeguards.

Classification

LLMMultimodal

Family: Claude

Access & deployment

APIHosted

Cloud

Weights: Closed

Key parameters

📏 Context: 200K

✓ Tools

📥 Input: text, image

Platforms

Anthropic Claude API Amazon Bedrock Vertex AI Microsoft Azure AI Foundry

Technical specification

Context window

200K

tokens

Max output tokens

64,000

tokens per response

Features:✓ Tool use

Modalities

⬇ Input

textimage

⬆ Output

textcode

Capabilities and applications

Native model capabilities

Coding

Generating, analysing and modifying code in many programming languages. Covers writing functions, debugging, refactoring, code review, and creating tests. Measured by benchmarks such as HumanEval and SWE-bench.

Category: coding

Reasoning

The model's ability to reason logically and solve complex problems.

Category: reasoning

Multi-step reasoning

Carrying out multi-step chains of reasoning across long, complex tasks.

Category: reasoning

Long context

Support for large context windows — tens to hundreds of thousands (or millions) of input tokens. Enables analysis of entire codebases, long documents, and many parallel conversations without losing earlier information. GPT-5.1 supports 400,000 tokens.

Category: language

Multilingual

Competence in many natural languages (from a few to over a hundred): understanding, generation, translation, and code-switching within a single conversation. Frontier models support a wide range of languages with comparable quality.

Category: language

Image understanding

Analysing and interpreting the content of images.

Category: vision

Function Calling

Category: planning

Parallel Tool Calls

Ability to invoke multiple external tools simultaneously while generating a response.

Category: reasoning

Planning

Forming and executing action plans for complex tasks.

Category: planning

Agentic capability

The model's ability to autonomously plan and execute multi-step tasks by sequentially using tools, maintaining context, and adapting to intermediate results.

Category: planning

Computer use

The model's ability to operate a computer interface by interpreting screenshots and generating actions such as clicks, typing, and navigating applications.

Category: planning