What is Claude Opus 4.5?
Claude Opus 4.5 is a frontier language model from Anthropic, released on November 24, 2025. It belongs to the Opus tier of the Claude family, which is intended for the most demanding reasoning, coding, research, and automation tasks. The model is available through the Claude API and through Amazon Bedrock, Google Cloud, Microsoft Foundry, and Claude Platform on AWS.
The canonical API model identifier is claude-opus-4-5-20251101, while claude-opus-4-5 is the shorter API alias. In practical terms, Opus 4.5 is intended for applications where a more capable model can justify higher token costs and potentially higher latency than smaller Sonnet- or Haiku-class alternatives.
It accepts text and image inputs and returns text. Images can be used for visual analysis, and supported documents can be supplied as context, but the model does not natively generate images, audio, or video.
What Claude Opus 4.5 is best at
Opus 4.5 is aimed at work that involves several connected decisions, large amounts of context, or interaction with external tools. Anthropic positions it for complex coding, agentic workflows, computer use, deep research, spreadsheets, presentations, financial modeling, and long-context content creation.
- Complex software engineering: debugging, refactoring, test generation, multi-file changes, and longer software-development tasks.
- Agentic applications: workflows in which the model plans actions, calls tools, evaluates results, and continues through multiple steps.
- Computer-use workflows: applications that connect Claude to supported computer-control tools. These systems still require application-level permissions, monitoring, and safeguards.
- Research and analysis: comparing evidence across documents, synthesizing findings, and producing structured reports.
- Enterprise work: document analysis, financial modeling, presentations, spreadsheets, and other high-value workflows where mistakes are costly.
- Visual understanding: interpreting images and visual content in supported documents, including visual PDF material.
These use cases describe the model’s intended positioning. They should not be read as a guarantee that every answer will be correct. High-impact workflows still need verification, access controls, and suitable testing.
Reasoning, coding, and tool support
Claude Opus 4.5 supports extended thinking, a mode in which the model can spend additional computation working through a difficult problem before producing its answer. The documented default effort is high. This is useful for tasks such as planning a multi-file code change, tracing a difficult bug, weighing evidence, or coordinating a sequence of tool calls. It can also increase response time and token usage, so extended reasoning is not automatically the best choice for simple requests.
For coding, the model is designed for long-horizon software engineering rather than only code completion. A coding agent can use it to inspect a repository, propose a plan, edit several files, generate tests, and respond to test results. The quality of such a system also depends on the surrounding tools, repository context, permissions, and validation process.
Opus 4.5 supports client-side and server-side tool use. Tools let an application provide functions such as search, database access, file operations, or external services. The model can request a tool call, while the application remains responsible for executing the action and returning the result. Structured outputs can constrain responses to a supplied JSON Schema, which is useful when software needs predictable fields. Structured outputs should not automatically be treated as a separate legacy JSON-mode capability.
Context window, modalities, and output limits
| Specification | Claude Opus 4.5 |
|---|---|
| Release date | November 24, 2025 |
| Canonical model ID | claude-opus-4-5-20251101 |
| Context window | 200,000 tokens |
| Maximum output | 64,000 tokens |
| Input types | Text and images |
| Output type | Text |
| Reasoning | Extended thinking |
| Knowledge cutoff | May 2025 reliable cutoff; August 2025 broader training-data cutoff |
| Streaming | Supported |
| Prompt caching | Supported |
| Batch processing | Supported |
A 200,000-token context window allows an application to provide substantial source material, conversation history, or project context in one request. It is not the same as guaranteed comprehension of every detail: large inputs still need careful organization, and applications should test how the model performs with their specific documents.
The reliable knowledge cutoff is May 2025, with August 2025 identified as the broader training-data cutoff. Web search, retrieval, and information supplied by an application can provide newer material during a request, but they do not change the model’s underlying knowledge cutoff.
Pricing and API costs
Anthropic lists Opus 4.5 at $5 per million input tokens and $25 per million output tokens. Input tokens are the text, images, instructions, and other material sent to the model; output tokens are the generated response. Long prompts and extensive generated answers can therefore produce materially different costs.
Prompt caching has separate prices. Five-minute cache writes cost $6.25 per million tokens, one-hour cache writes cost $10 per million tokens, and cache reads cost $0.50 per million tokens. The Batch API provides a 50% discount on input and output token pricing. Tool use is charged through normal input and output token usage, while some server-side tools may add separate usage-based fees.
The main cost trade-off is straightforward: Opus 4.5 may be appropriate when solving a difficult task correctly is more valuable than minimizing per-request cost, but it is not the natural choice for every high-volume or low-latency workload. A smaller Claude model may be more economical when the task does not require Opus-level reasoning or long-horizon planning.
Strengths and limitations
Based on the supplied model information, the main strengths of Claude Opus 4.5 are its coding capability, multi-step reasoning, tool calling, image understanding, long-context handling, and support for demanding enterprise workflows. Its combination of extended thinking and a 64,000-token output limit can be useful for detailed plans, extensive code changes, and long-form analysis.
There are also important limitations:
- It produces text only and does not natively generate images, audio, or video.
- Its 200,000-token context window is smaller than the 1-million-token context offered by some newer Claude models.
- Higher capability comes with higher pricing and potentially greater latency than Sonnet- or Haiku-class models.
- Extended thinking can increase token consumption and response time.
- Usage, tool availability, and platform access can vary by provider and deployment.
- The model is classified as active legacy, so new projects may have a longer-term maintenance advantage if they use a newer recommended Opus model instead.
When to choose Claude Opus 4.5
Choose Claude Opus 4.5 when the task benefits from careful reasoning, substantial context, image understanding, and repeated interaction with tools. Suitable examples include a coding agent making coordinated changes across a repository, a research system comparing a large collection of documents, an enterprise assistant analyzing financial material, or a computer-use workflow that needs detailed planning before taking actions.
It is less suitable when the main requirement is the lowest possible cost, the shortest response time, or the newest model lifecycle. For simple classification, routine extraction, short answers, or high-volume generation, a smaller and faster model may provide a better cost-to-performance ratio. If the application requires a 1-million-token context window, a newer model with that limit may also be more appropriate.
Because Anthropic lists Opus 4.5 as Active (legacy) as of September 24, 2026, teams starting a new deployment should compare it with the newer Opus model recommended by Anthropic. Existing applications can continue using it while it remains available, but they should test a migration path before the documented retirement window, which is no sooner than November 24, 2026.
Availability and lifecycle
Claude Opus 4.5 is available through Anthropic’s API and through Amazon Bedrock, Google Cloud, Microsoft Foundry, and Claude Platform on AWS. Exact access, regional availability, quotas, and billing arrangements can differ between these platforms.
Anthropic’s lifecycle information identifies the model as active but legacy and recommends migration to Claude Opus 5.5. The no-sooner-than November 24, 2026 retirement date is a minimum-not-before commitment rather than a guaranteed final shutdown date. Applications that depend on Opus 4.5 should pin and monitor the model identifier, test newer replacements, and avoid assuming indefinite availability.