Claude Opus 5.5
Claude Opus 5.5 is the model Anthropic recommends as the starting point for most workloads, built for long-running agentic coding and knowledge work. Released September 22, 2026, it succeeds Claude Opus 5 at a lower per-token price and keeps a 1M-token context window.
Specifications
- Context window
- 1Mabout 750,000 words, or 1,500 pages
- Max output
- 125Ktokens per response
- Input price
- $4per 1M tokens
- Output price
- $20per 1M tokens
- Cached input
- $0.20per 1M tokens
- Weights
- ClosedProprietary
- Parameters
- Undisclosed
- Input types
- Text, Images, PDF
- Output types
- Text
- Reasoning mode
- Yes
- Tool calling
- Yes
- Released
- Sep 22, 2026Current
Standard rates; no surcharge across the 1M-token window. Batch API 50% off. Fast mode (research preview, Claude API only) costs $8 input / $40 output. US-only inference adds 1.1x.
What it costs in practice
| Workload | Monthly cost at list price |
|---|---|
| Support chatbot30,000 conversations a month, 2,000 input and 400 output tokens each | $480 |
| Document summaries2,000 documents a month, 12,000 input and 800 output tokens each | $128 |
| Coding agent1,000 tasks a month, 60,000 input and 6,000 output tokens each | $360 |
Standard rates, no caching or batch discounts. Run your own numbers.
Strengths
- Anthropic's recommended default for most workloads
- 1M-token context with no long-context surcharge
- Up to 128K output tokens, or 300K on the Message Batches API beta
Trade-offs to weigh
- Thinking is always on and cannot be disabled
- Forced tool use returns an error, a breaking change from Claude Opus 5
Where it fits
Anthropic positions Claude Opus 5.5 for:
Where you can use it
- API
- Claude apps
- Amazon Bedrock
- Google Vertex AI
- Microsoft Azure AI Foundry
- Claude Platform on AWS
- OpenRouter
Alternatives to consider
| Model | Tier | Context | Input / output per 1M | |
|---|---|---|---|---|
| Gemini 3.1 ProGoogle | Frontier | 1M | $2 / $12 | Compare |
| Kimi K3Moonshot AI | Frontier | 1M | $3 / $15 | Compare |
| GPT-6 AstraOpenAI | Frontier | 1.05M | $10 / $50 | Compare |
| Grok 4.7xAI | Frontier | 500K | $2 / $6 | Compare |
Frequently asked questions
How much does Claude Opus 5.5 cost?
Claude Opus 5.5 lists at $4 per million input tokens and $20 per million output tokens, with cached input at $0.20 (checked October 10, 2026). Standard rates; no surcharge across the 1M-token window. Batch API 50% off. Fast mode (research preview, Claude API only) costs $8 input / $40 output. US-only inference adds 1.1x. Confirm current rates on the provider's pricing page before you commit.
What is the context window of Claude Opus 5.5?
Claude Opus 5.5 accepts up to 1,000,000 tokens of context (about 750,000 words, or 1,500 pages), and it can write up to 125K tokens in a single response. Long prompts cost more and can be slower, so most apps send only what the task needs.
Is Claude Opus 5.5 open source?
No. Claude Opus 5.5 is a proprietary model from Anthropic; its weights aren't published. You can use it through the Anthropic API and through Claude apps, Amazon Bedrock, Google Vertex AI, Microsoft Azure AI Foundry, Claude Platform on AWS, OpenRouter.
What is Claude Opus 5.5 best for?
Anthropic positions Claude Opus 5.5 for coding, agents, reasoning, long documents. It accepts text, images, pdf as input, has a reasoning (thinking) mode and supports tool calling. Test it on a sample of your own tasks before you choose it for production.
Sources
- platform.claude.com/docs/en/models/opus-5-5/overview
- platform.claude.com/docs/en/about-claude/pricing
- platform.claude.com/docs/en/models/overview.md
- platform.claude.com/docs/en/build-with-claude/pdf-support
- openrouter.ai/anthropic/claude-opus-5.5
Facts checked against these pages on October 10, 2026. Spot an error? Tell us.
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