01
Overview
Claude Opus 5.5 is Anthropic’s newest Opus model for coding, agents and professional knowledge work. Anthropic released it on September 22, 2026 and now recommends Opus 5.5 as the starting point for most workloads, reserving the more expensive Fable 5.1 tier for demanding reasoning or long-horizon work where Opus 5.5 at higher effort still falls short.
02
Release and availability
Opus 5.5 is available through Claude for Pro, Max, Team and Enterprise users. Developers can access it through the Claude Platform using the API model ID claude-opus-5-5. Anthropic also says it is available through Amazon Web Services, Google Cloud and Microsoft Foundry. Exact cloud-provider identifiers and regional availability should be checked against each provider before deployment.
03
Context window and output limit
Anthropic’s current model documentation lists a 1 million-token context window and a maximum output of 128,000 tokens. Adaptive thinking is always on, with medium as the documented default effort. A large context window is useful for repositories, research corpora and long-running agent histories, but teams should still test retrieval quality and cost on their own workloads.
04
Claude Opus 5.5 API pricing
Anthropic lists standard Claude API pricing at $4 per million input tokens and $20 per million output tokens. That is 20% below Opus 5’s $5/$25 base rates. Prompt-cache reads are $0.20 per million tokens, 60% below Opus 5’s $0.50 cache-read rate.
Anthropic says typical token-billed workloads cost about 40% less to run than Opus 5 because Opus 5.5 combines lower token prices with lower token usage per task. That 40% figure is a vendor estimate, not a guaranteed saving for every application. Real cost depends on prompts, cache hit rate, effort, tool calls and output length.
05
Fast mode
Fast mode is available for Opus 5.5 in Claude Code and on the Claude Platform. Anthropic advertises up to 2.5x faster speed and lists Fast mode at $8 per million input tokens and $40 per million output tokens. Treat the speed figure as vendor-reported; latency varies with workload and infrastructure.
06
What changed from Opus 5
The upgrade combines lower list pricing with greater token efficiency and stronger vendor-reported performance in coding, agentic workflows, computer use and professional knowledge work. Anthropic also emphasizes clearer communication: putting important information first, reducing jargon and following writing rules more closely.
For production teams, the important question is not whether 5.5 is newer but whether it improves cost per successful task. Existing Opus 5 applications should compare quality, token use, latency, tool-call count and safeguard behavior before changing defaults.
07
Coding and agents
Anthropic positions Opus 5.5 as its strongest Opus model for agentic coding. The company says it handles long-running work in large codebases, including feature development, debugging, refactoring and code review. For agents, Anthropic highlights multi-tool orchestration, subagent coordination, memory across sessions and long-running execution with less oversight.
Those are vendor capability claims. They are plausible reasons to evaluate the model, not guarantees that every agent will become more reliable without application-level testing, observability and guardrails.
08
Vision, computer use and enterprise work
Opus 5.5 supports text and image input and text output, alongside tool use and vision. Anthropic positions it for document and chart analysis, computer-use workflows, spreadsheets, slides, professional documents and financial analysis. Current Claude model documentation lists the model’s reliable knowledge cutoff as June 2026.
09
Benchmarks
Anthropic’s launch page reports improvements across agentic coding, knowledge work, computer use and reasoning evaluations. The company also documents important benchmark conditions: many Opus 5.5 results use adaptive thinking at max effort, Terminal-Bench 4.0 uses xhigh effort, and production safeguards were enabled. Some benchmark tasks can fall back to other Claude models when safeguards intervene.
These numbers should therefore be described as Anthropic-published launch results unless an evaluation is independently reproduced. Benchmark harnesses, effort settings, tools and safeguard routing can materially affect comparisons.
10
Safeguards
Opus 5.5 is the first Opus release with safeguards similar in class to Fable 5.1 for cybersecurity, biology and anti-distillation. Anthropic says safeguard interventions can route cybersecurity tasks to Claude Opus 4.8 and biology or frontier-LLM-development tasks to Claude Opus 5. This routing matters when interpreting both real-world behavior and benchmark results.
11
Who should use Opus 5.5?
The model is a strong candidate for teams running coding agents, codebase analysis, multi-step research, professional document workflows, computer-use agents and other workloads where Opus-level intelligence matters but Fable pricing is difficult to justify. Anthropic’s own model guide recommends starting with Opus 5.5 for most workloads.
Lower-cost Claude tiers can still make more sense for high-volume or latency-sensitive work. Model routing should be based on evals and total task economics rather than using the most capable tier everywhere.
12
FAQ
When did Claude Opus 5.5 launch?
September 22, 2026.
What is the API model ID?
claude-opus-5-5 on the Claude API.
How much does Claude Opus 5.5 cost?
Anthropic currently lists $4/M input tokens and $20/M output tokens, with cache reads at $0.20/M. Recheck pricing before budgeting because model prices can change.
What is the context window?
1 million tokens, with up to 128K output tokens according to Anthropic’s current model documentation.
Is Fast mode available?
Yes. Anthropic lists Fast mode in Claude Code and the Claude Platform at $8/M input and $40/M output, with up to 2.5x faster speed.
Is Opus 5.5 better than Fable 5.1?
Anthropic says Opus 5.5 performs at Fable 5.1’s level on most work, but its model guide still recommends Fable 5.1 for demanding reasoning and long-horizon agentic tasks when Opus 5.5 at higher effort is insufficient. Treat task-specific evals as more useful than a universal winner claim.
13
Bottom line
Claude Opus 5.5 is a high-priority model release because it improves both capability and economics in a tier already widely used for serious coding and agent workflows. The early search opportunity is strongest around pricing, API setup, migration from Opus 5, Fast mode, benchmarks and the decision between Opus 5.5 and Fable 5.1.
Sources
Primary and supporting sources
Use the linked documentation to check current pricing, access and product behaviour. The dates above describe this article; they do not guarantee that every vendor claim remains current.