01
Overview
Claude Opus 5.5 is available through Anthropic’s Claude API under the model ID claude-opus-5-5. For developers, the release is notable not only because Anthropic positions it as a stronger Opus model, but because its standard token rates and prompt-cache read price are lower than Opus 5.
02
Claude Opus 5.5 model ID
Use claude-opus-5-5 when selecting the model on the Claude API. Anthropic’s Models API can also be used to inspect available model capabilities and token limits programmatically. If you deploy through AWS, Google Cloud or Microsoft Foundry, verify the provider-specific identifier instead of assuming the native Claude API ID is identical.
03
Standard API pricing
Anthropic currently lists Opus 5.5 at $4 per million input tokens and $20 per million output tokens. Opus 5 was $5/M input and $25/M output, so the base token rates are 20% lower.
This is usage pricing, not a promise about the total cost of an application. Agent workloads can make many calls, use tools repeatedly and carry large contexts. Measure cost per completed task rather than comparing token rates alone.
04
Prompt-cache pricing
Anthropic lists cache reads for Opus 5.5 at $0.20 per million tokens. The Opus 5 cache-read price was $0.50/M, making the new read rate 60% lower.
That can matter substantially for coding and agent systems that repeatedly reuse a large repository, system prompt, tool definitions or conversation state. Savings depend on how much content is actually cacheable and how often cached prefixes are reused.
Anthropic says typical token-billed Opus 5.5 workloads cost around 40% less than Opus 5 when lower list prices and reduced token use per task are combined. Treat this as Anthropic’s workload estimate rather than a universal discount.
05
Fast mode pricing
Opus 5.5 Fast mode is available in Claude Code and on the Claude Platform. Anthropic lists it at $8/M input and $40/M output and advertises up to 2.5x faster speed.
Fast mode therefore doubles the standard input/output rates. It is best evaluated where latency has enough business value to justify the premium—for example interactive coding loops or time-sensitive agents. Benchmark real end-to-end latency rather than assuming every request will be exactly 2.5x faster.
06
Context and output limits
Anthropic’s model overview lists a 1M-token context window and 128K maximum output for Opus 5.5. Adaptive thinking is always on and medium is the documented default effort.
A 1M context limit does not mean every application should send enormous prompts. Larger prompts cost more, can increase latency and may make retrieval harder. Use caching, retrieval and context management where they improve task economics.
07
A minimal implementation pattern
A production integration should keep the model identifier configurable rather than hard-coding it across the application. Send requests through Anthropic’s current Messages/API SDK interface, define tool schemas explicitly when using agents, log token usage and cache metrics, and test effort settings against your own quality threshold.
Before production rollout, verify the current Anthropic SDK and API examples because request fields and supported features can evolve faster than a static tutorial.
08
Standard vs Fast mode
Standard mode is the default economic choice for asynchronous agents, research, batch-like workflows and tasks where a few extra seconds do not matter. Fast mode is more relevant to interactive developer tools or workflows where latency directly affects user productivity.
Do not choose solely on per-token price. A faster mode can still be economical if it reduces waiting or improves iteration speed, while standard mode can be preferable when throughput and cost matter more than response latency.
09
Opus 5.5 vs Fable 5.1 economics
Anthropic currently lists Fable 5.1 at $10/M input and $50/M output, compared with $4/$20 for Opus 5.5. Anthropic’s model guide recommends starting with Opus 5.5 for most workloads and moving to Fable 5.1 for demanding reasoning and long-horizon agentic work when Opus 5.5 at higher effort still falls short.
That makes an eval-driven escalation pattern sensible: use Opus 5.5 as the default candidate, then route only the tasks that demonstrably benefit from Fable. This is an architectural suggestion, not an Anthropic guarantee that routing will always reduce cost.
10
Deployment checklist
Confirm the current model ID and lifecycle status; verify standard, cache and Fast pricing; test context/output requirements; measure cache hit rates; compare effort levels; inspect safeguard behavior on your domain; evaluate latency and task-success rate; and confirm provider-specific identifiers and availability if using AWS, Google Cloud or Microsoft Foundry.
11
FAQ
What is the Claude Opus 5.5 API model ID?
claude-opus-5-5 on Anthropic’s native Claude API.
What does the API cost?
Anthropic currently lists $4/M input and $20/M output for standard mode.
How much do cache reads cost?
$0.20 per million tokens according to Anthropic’s launch page.
How much does Fast mode cost?
$8/M input and $40/M output. Anthropic advertises up to 2.5x faster speed.
What is the context window?
1 million tokens, with a maximum output of 128K tokens according to Anthropic’s current model overview.
Is Opus 5.5 on cloud providers?
Anthropic says it is available through AWS, Google Cloud and Microsoft Foundry. Verify provider-specific model IDs and regional availability before deploying.
12
Bottom line
Opus 5.5 materially changes Opus economics: lower base token rates, much cheaper cache reads and an optional premium Fast mode. The practical migration decision should come from application-specific evals that combine quality, latency, token usage, cache behavior and total cost per successful task.
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.