The source says API input and output prices are 20% lower than Opus 5, while cache reads are 60% lower. It also lists Opus 5.5 API prices of $4 per million input tokens, $20 per million output tokens, and $0.20 per million cache reads.
The mechanism is repeated context: every turn in a Claude Code task resends the accumulated conversation, while most previously seen material can be billed as a cache read. The mechanism is repeated context: every turn in a Claude Code task resends the accumulated conversation, while most previously seen material can be billed as a cache read. This makes turn count, cache-hit rate, output—including billed thinking—and model choice jointly determine a task receipt. Anthropic’s illustrated 40-turn example processes roughly 2.8 million input tokens despite context peaking at 120K tokens; at a 90% cache-hit rate, it estimates input cost at about $1.62.
Why now is that lower cache-read pricing makes session design a more visible cost lever for long-running coding agents. Why now is that lower cache-read pricing makes session design a more visible cost lever for long-running coding agents. Teams should treat tests, builds, scoped tasks, and batching tool calls as economic controls when they reduce retries or unnecessary turns. The first implication is that procurement and evaluation should compare cost per successfully completed task, not a model’s headline token rate. The first implication is that procurement and evaluation should compare cost per successfully completed task, not a model’s headline token rate.
The evidence boundary is that Anthropic presents list prices and best-effort illustrations, says results vary by task, and excludes cache writes from its calculator. The evidence boundary is that Anthropic presents list prices and best-effort illustrations, says results vary by task, and excludes cache writes from its calculator. The first watch condition is whether independent production measurements show that Opus 5.5 reduces turns or output tokens enough to extend savings beyond the published price cut. The first watch condition is whether independent production measurements show that Opus 5.5 reduces turns or output tokens enough to extend savings beyond the published price cut.