# Claude Sonnet 4.5

> The model that topped SWE-bench Verified and ran agents autonomously for 30+ hours.

- Maker: Anthropic
- Line: Claude Sonnet
- Canonical page: https://ai-tldr.dev/models/claude-sonnet-4-5/
- Updated: 2026-06-17

## In short

Claude Sonnet 4.5 is the model that topped SWE-bench Verified and ran agents autonomously for 30+ hours. Anthropic released it on 29 September 2025 as an API-only model. It has a 1M-token context window and costs $3.00 per million input tokens and $15.00 per million output tokens. You can use it through Anthropic, Amazon Bedrock and Google Vertex AI.

## Facts

| Fact | Value | Source |
| --- | --- | --- |
| Context window | 1M (max output 64K) | [1] |
| Input price | $3.00 per million tokens | [2] |
| Output price | $15.00 per million tokens | [2] |
| Licence | Proprietary · API only | [1] |
| Released | 29 September 2025 | [3] |
| Knowledge cutoff | January 2025 | [1] |

## Sources

1. [Amazon Bedrock model card](https://docs.aws.amazon.com/bedrock/latest/userguide/model-card-anthropic-claude-sonnet-4-5.html)
2. [Claude Sonnet 4.5 pricing](https://platform.claude.com/docs/en/about-claude/models/overview.md)
3. [Introducing Claude Sonnet 4.5](https://www.anthropic.com/news/claude-sonnet-4-5)

## Overview

Claude Sonnet 4.5 was released on September 29, 2025, and at launch posted the highest SWE-bench Verified score of any Claude model to date: 77.2% (rising to 82.0% with parallel test-time compute). It also set a record on OSWorld for computer use at 61.4%, well above the 42.2% Sonnet 4 had managed. Anthropic positioned it as a drop-in replacement for Sonnet 4 at the same price.

Sonnet 4.5 is a hybrid reasoning model with extended thinking, and it was the model that introduced sustained long-horizon autonomy: Anthropic reported it could stay on task for more than 30 hours on complex multi-step work. Alongside the model, Anthropic shipped context editing, a memory tool, checkpoints, and a VS Code integration to support these long-running agentic workflows.

Sonnet 4.5 carries a 200K token context window (with a 1M token beta), 64K max output tokens, and supports text and vision input. It remains available on the Claude API as claude-sonnet-4-5, on Amazon Bedrock, and on Vertex AI, and is priced at $3 / $15 per million tokens.

## Benchmarks

- SWE-bench Verified: 77.2% ([source](https://www.anthropic.com/news/claude-sonnet-4-5))
- OSWorld (computer use): 61.4% ([source](https://www.anthropic.com/news/claude-sonnet-4-5))

## Pricing

- Input: $3.00 per million tokens
- Output: $15.00 per million tokens

Same price as Sonnet 4; one-fifth the price of Opus 4.1.

Source: https://platform.claude.com/docs/en/about-claude/models/overview.md

## Strengths

- Record SWE-bench Verified (77.2%) and OSWorld (61.4%) scores at launch
- Sustained autonomous agent operation for 30+ hours on complex tasks
- Extended thinking for multi-step reasoning in math, science and coding
- Shipped with context editing, memory tool, and checkpoints for agents
- Same $3/$15 pricing as Sonnet 4, a fifth of Opus 4.1's cost

## Best for

- Long-running autonomous coding agents and multi-hour build tasks
- Computer-use automation across desktop and browser interfaces
- Agentic workflows needing memory and context-editing tooling
- Domain-specific knowledge work in finance, law, medicine and STEM
- IDE-integrated coding assistance (VS Code, Claude Code)

## How to access

- [Anthropic](https://platform.claude.com/docs/en/about-claude/models/overview) — model id `claude-sonnet-4-5`
- [Amazon Bedrock](https://docs.aws.amazon.com/bedrock/latest/userguide/model-card-anthropic-claude-sonnet-4-5.html) — model id `anthropic.claude-sonnet-4-5-20250929-v1:0`
- [Google Vertex AI](https://platform.claude.com/docs/en/build-with-claude/claude-on-vertex-ai) — model id `claude-sonnet-4-5@20250929`

## Claude Sonnet versions

- [Claude Sonnet 4.6](https://ai-tldr.dev/models/claude-sonnet-4-6/) (17 February 2026)
- Claude Sonnet 4.5 (29 September 2025) — this page
- [Claude Sonnet 4](https://ai-tldr.dev/models/claude-sonnet-4/) (22 May 2025)
- [Claude 3.7 Sonnet](https://ai-tldr.dev/models/claude-3-7-sonnet/) (24 February 2025)
- [Claude 3.5 Sonnet (new)](https://ai-tldr.dev/models/claude-3-5-sonnet-v2/) (22 October 2024)
- [Claude 3.5 Sonnet](https://ai-tldr.dev/models/claude-3-5-sonnet/) (20 June 2024)
- [Claude 3 Sonnet](https://ai-tldr.dev/models/claude-3-sonnet/) (4 March 2024)

## FAQ

### What was special about Claude Sonnet 4.5?

At its September 2025 launch it had the best SWE-bench Verified score of any Claude model (77.2%) and the best OSWorld computer-use score (61.4%), plus the ability to run agents autonomously for over 30 hours.

### How much does Claude Sonnet 4.5 cost?

$3 per million input tokens and $15 per million output tokens, the same as Sonnet 4 and one-fifth the price of Opus 4.1.

### What is the context window?

200K tokens standard, with a 1 million token beta context window and up to 64K output tokens.

### Is Sonnet 4.5 still available?

Yes. It remains active on the Claude API as claude-sonnet-4-5, and on Amazon Bedrock and Vertex AI, though Anthropic recommends Sonnet 4.6 for new work.

## Links

- [Introducing Claude Sonnet 4.5](https://www.anthropic.com/news/claude-sonnet-4-5)
- [Models overview (Claude docs)](https://platform.claude.com/docs/en/about-claude/models/overview)
- [Amazon Bedrock model card](https://docs.aws.amazon.com/bedrock/latest/userguide/model-card-anthropic-claude-sonnet-4-5.html)
- [Caylent: Highest-scoring Claude on SWE-bench](https://caylent.com/blog/claude-sonnet-4-5-highest-scoring-claude-model-yet-on-swe-bench)
- [InfoQ: Sonnet 4.5 tops SWE-bench Verified](https://www.infoq.com/news/2025/10/claude-sonnet-4-5/)
- [DataCamp: Sonnet 4.5 review](https://www.datacamp.com/blog/claude-sonnet-4-5)
- [Claude Sonnet 4.5 pricing](https://platform.claude.com/docs/en/about-claude/models/overview.md)

Source: AI/TLDR LLM registry, https://ai-tldr.dev/models/claude-sonnet-4-5/