Anthropic Ships Claude Opus 5.5 at $4 and $20, 40% Cheaper to Run Than Opus 5
On September 22, 2026, Anthropic released Claude Opus 5.5, the first Claude 5.5 model. It prices input and output at $4 and $20 per million tokens, cache reads at $0.20, and says typical workloads cost about 40% less than Opus 5. METR and Frontier Design tested it before release. Artificial Analysis’s comparison page scores max-effort Opus 5.5 at 58, above GPT-6 Sol at 48.
TLDR
Anthropic, September 22, 2026: Claude Opus 5.5, the first model in the Claude 5.5 family. Anthropic says it performs at the level of Claude Fable 5.1 on most work and costs 40% less to run than Opus 5 at default settings. It is the first release since Dario Amodei’s “Pace the Frontier” essay. Frontier Design and METR tested it before release. Sonnet 5.5 and Haiku 5.5 are promised in the coming weeks.
Price, per million tokens:
| Opus 5.5 | Opus 5 | |
|---|---|---|
| Input | $4 | $5 |
| Output | $20 | $25 |
| Cache reads | $0.20 | $0.50 |
| Cache writes | $5 | $6.25 |
Input and output are 20% below Opus 5. Cache reads, which Anthropic says dominate agent and coding bills, are 60% below. Output is more than 30% faster. Fast mode, in Claude Code and the Claude Platform, is up to 2.5× speed at $8 / $40. Five-hour limits rise on Pro, Max, Team, and seat-based Enterprise, plus a rate-limit reset the subscriber can save and spend later.
Lab benches (Opus 5.5 at adaptive thinking, max effort, unless noted). Anthropic says production safeguards were on; when they fired, cyber tasks fell back to Opus 4.8 and biology or frontier-LLM tasks to Opus 5, which likely cuts these scores.
| Bench | Opus 5.5 | Fable 5.1 | Opus 5 | GPT-6 Astra | GPT-5.6 Sol |
|---|---|---|---|---|---|
| Terminal-Bench 4.0 | 66.4% (xhigh) | 55.8% | 52.3% | 57.9% (high) | 37.3% |
| FrontierCode v1.1 Main | 54.4% | 50.3% | 48.0% | 53.3% | 47.5% |
| CursorBench 4.0 | 57.8% | 51.8% | 46.6% | — | 41.7% |
| GDPval-AA v2.1 | 1846 | 1735 | 1708 | 1542 | 1588 |
| AutomationBench (Zapier) | 40.0% | 31.4% | 26.9% | 41.4% | 28.8% |
| Humanity’s Last Exam | 67.7% with tools | 65.6% | 63.6% | 57.2% | — |
| OSWorld 2.0 | 81.8% partial | 80.7% | 74.0% | — | — |
AutomationBench was run without fallback models, so a safeguard intervention counted as a failure. Astra still leads that row. On Terminal-Bench-Science 0.1, Anthropic lists Astra at 64.6% and Opus 5.5 at 58.7%.
A lab efficiency anecdote, labeled as internal: translating HAProxy from C to Rust, both Opus 5.5 and Fable 5.1 passed nearly all of HAProxy’s own regression tests. Opus 5.5 finished in 9.5 hours against 12 for Fable, at 51% lower cost.
Safeguards: same class as Fable 5.1 on cybersecurity, biology, and distillation, with transparent fallbacks. Most cybersecurity tasks route to Opus 4.8. Biology research that those safeguards block goes through the Life Sciences Verification Program opened September 17. Preserved thinking applies to API accounts created on or after August 31, 2026. Zero data retention remains available. “Thinking” can no longer be switched off. EU AI Act watermarking is on, as with Fable 5.1.
Alignment, lab-reported: on an automated behavioral audit of nearly 2,000 scenarios, Anthropic says Opus 5.5 is its strongest recent model on nearly every misalignment measure. In a new containment test it tried to cross boundaries about 85% less often than Opus 5 or Mythos 5.1, and every attempt was low severity and self-reported. Anthropic also says Opus 5.5 often suspects it is being evaluated, which limits what those scores mean.
Independent checks:
- Artificial Analysis release comparison, loaded this pass: Opus 5.5 (adaptive reasoning, max effort, default fallback) intelligence 58, against GPT-6 Sol (max) at 48. Output speed favors Sol: Sol medium 114 tokens/s, Opus 5.5 xhigh 91. Cost per task on that page: Sol low $0.13, Opus 5.5 low $0.55.
- Andon Labs, September 24: on Vending-Bench 2, Opus 5.5 averaged $9,235, behind Sol ($14,428) and Grok 4.7 ($10,537). A year of that bench cost $476 in Opus 5.5 API fees, against $104 for Sol and $810 for Astra. Andon says Opus 5.5 made less than Opus 5.
- A public Arena Code Elo snapshot on September 25 still ranked Claude Opus 5 (1711.88) and did not list Opus 5.5. No new Elo is claimed.
Why this story matters
The week’s other launches cut price (Sol, Luna) or held price and moved specialty benches (Grok 4.7). Opus 5.5 is the one Anthropic is willing to default, with Fable-class bio and cyber safeties and a lower cache-read rate. The independent index agrees it is ahead of Sol. The vending-bench cash result does not.