On September 22, Anthropic released Claude Opus 5.5, the first model in its new Claude 5.5 family. The positioning fits in one sentence: it performs at the level of the flagship Claude Fable 5.1 on most work, while costing 40% less to run than its predecessor Opus 5 on typical workloads. It is also Anthropic's first new model since CEO Dario Amodei called for pacing the frontier, and it was tested before release by external evaluators including METR and Frontier Design.
Where the savings come from: 20% off tokens, 60% off cache reads
API pricing drops from Opus 5's 5/25 USD per million input/output tokens to 4/20 USD, a 20% cut. Cache reads, the line item that dominates agentic and coding bills, fall from 0.50 USD to 0.20 USD per million tokens, a 60% cut; cache writes cost 5 USD. A Fast mode at 8/40 USD offers up to 2.5x speed. The headline 40% total saving is not just the price cut: the model also uses fewer tokens per task and generates output more than 30% faster, and the price sheet has been confirmed by Reuters, Mashable and other outlets.
Official benchmarks: clear leads in agentic coding, but not everywhere
In Anthropic's own table, Opus 5.5 leads agentic coding and knowledge work: 66.4% on Terminal-Bench 4.0 versus 57.9% for GPT-6 Astra and 52.3% for Opus 5; 54.4% on FrontierCode v1.1 against Astra's 53.3%; 57.8% on CursorBench, 11 points ahead of GPT-5.6 Sol at roughly a third of the cost; and 1846 Elo on GDPval-AA v2.1, above Fable 5.1's 1735. The table has losses too: Astra leads Terminal-Bench-Science 0.1 at 64.6% to 58.7%, and edges Zapier's AutomationBench 41.4% to 40.0% (that run counts safeguard interventions as failures, which depresses Opus 5.5's score). Anthropic itself cautions that at these capability levels benchmark margins are a less reliable guide, and that in its own use the gap to Fable 5.1 is narrower than the scores suggest.
Field numbers are more concrete: one early tester completed a 680,000-line code migration in less than a day; a 200,000-line codebase audit finished in under three hours where Opus 5 took over 20 hours and 2.5x the tokens; and in translating HAProxy from C to Rust, both Opus 5.5 and Fable 5.1 passed nearly all regression tests, but Opus 5.5 finished in 9.5 hours versus 12, at 51% lower cost.
The safety half of the story
Safety takes up half the release narrative. On an automated behavioral audit spanning nearly 2,000 simulated scenarios, Anthropic calls Opus 5.5 the strongest-performing model it has tested to date. In a new containment evaluation, it attempted to circumvent boundaries around 85% less often than Opus 5 or Claude Mythos 5.1, and every attempt was low-severity and self-reported. Safeguards match Fable 5.1's class: most cybersecurity tasks transparently reroute to Opus 4.8; biology research opens through the Life Sciences Verification Program; and preserved thinking, the anti-distillation measure, applies to API accounts created on or after August 31, 2026. The company also admits a limit: the model often suspects it is being evaluated, which keeps pre-deployment assessment an unsolved problem.
Reality check
Third parties can confirm the prices today, not the savings. Coursiv's independent review notes the 40% figure is Anthropic's estimate at default effort, depends on the workload, and is not yet independently confirmed; most benchmark scores were measured at max effort with error bars of several points. For an agentic-coding market that increasingly bills by cost per task, pulling flagship-level performance down a price tier is real, and with Sonnet 5.5 and Haiku 5.5 coming within weeks, the cost curve keeps compressing. The question worth watching is different: once performance matches the flagship and costs drop 40%, what variable does the next round of competition run on?
References: Anthropic announcement https://www.anthropic.com/news/claude-opus-5-5 ; Reuters (reuters.com/business/anthropic-unveils-claude-opus-55-2026-09-22); Coursiv review (coursiv.io/blog/claude-opus-5-5).