Anthropic released Claude Opus 5 on July 24, priced at $5 per million input tokens—identical to its predecessor Opus 4.8 and exactly half the cost of Fable 5—while outperforming Fable 5 across most major benchmarks. The new model is now the default on Claude Max and the strongest option on Claude Pro, effectively replacing Fable 5 as the go-to choice for most subscribers.

Opus 5 is cheaper for businesses to run than Anthropic's lead model, Claude Fable 5, which the company had positioned as its everyday frontier product for paying users. It also outperforms Fable 5 on several significant benchmarks. For companies building products on AI APIs, where token costs scale directly with user volume, a model that matches or exceeds frontier performance at half the price can meaningfully shift unit economics.

Anthropic's Model Tier Structure

Anthropic's lineup spans four tiers. Haiku is fast and inexpensive. Sonnet is mid-range. Opus serves as the heavy workhorse. Above those sits the Mythos class, a tier Anthropic introduced this spring, which includes Claude Fable 5 for the public and Claude Mythos 5, a version with fewer restrictions available through Project Glasswing for vetted cybersecurity researchers and critical infrastructure operators.

Fable 5 has had a turbulent run as the subscriber flagship. It launched June 9, only to be pulled globally three days later after the U.S. government issued an emergency export control order citing a jailbreak vulnerability. It returned June 30 but immediately shifted to a credits-only model, no longer included in standard plans. Opus 5 now fills the slot Fable 5 could not hold.

Lovable, a developer platform with millions of users, ran Opus 5 on its internal evaluations and noted the gains extend beyond raw scores. "It isn't just better on our hardest agentic coding tasks, up 22% over Opus 4.7, it's steadier, with far less variance run to run," Fabian Hedin said in a statement shared by Anthropic.

Benchmark Results

Opus 5 beats Fable 5 on nearly every metric relevant to everyday users, despite not carrying the Mythos-class designation.

On Frontier-Bench v0.1—a benchmark testing whether AI coding agents can complete real software engineering tasks end-to-end, scored as a percentage of tasks passed—Opus 5 reached 43.3%. Fable 5 scored 33.7%, while OpenAI's GPT-5.6 Sol, Anthropic's primary commercial rival, scored 34.4%.

The widest margin appeared on ARC-AGI-3, a test of genuine problem-solving built around novel puzzles a model could not have memorized from training data, scored as a percentage of puzzles solved. Opus 5 hit 30.2%; GPT-5.6 Sol scored 7.8%; and Fable 5 was not tested at all.

On GDPval-AA v2—a knowledge work benchmark scored via Elo ratings, the chess-style ranking system used to measure relative performance on real professional tasks—Opus 5 reached 1,861, compared to Fable 5's 1,747 and GPT-5.6 Sol's 1,736.

Zapier tested Opus 5 on AutomationBench, an evaluation scoring whether a model can carry a full business workflow from start to finish without human intervention. Their verdict: the model "took a raw account-health workbook and ran a full churn-prevention sequence end to end: flagging at-risk accounts, alerting the right owner, and summarizing for retention ops. Previous models didn't pass; Opus 5 hit 100%."

Anthropic is also positioning Opus 5 as a research upgrade. Ultima Genomics, a DNA sequencing company, said the model "behaves more like a careful scientist than any model we've run. It reaches for the right statistical tests to rule out confounders, cross-checks its own results by independent methods, and stays on track through long multi-step analyses."

That said, legal and health are the only two domains in which Fable 5 excels by a slim margin.

Broader Competitive Landscape

The release comes a week after Moonshot AI, a Beijing-based startup backed by Alibaba, unveiled Kimi K3—a 2.8-trillion-parameter open-weight model, meaning anyone can download the underlying code to run it independently. Moonshot describes it as the world's largest open AI system. Independent benchmarks consistently rank Kimi K3 third overall, behind both Fable 5 and GPT-5.6 Sol, though it outperforms those two in specific areas. That open-weight approach, which contrasts with the API-only access model used by Anthropic and OpenAI, lets organizations run models on their own hardware—though a 2.8-trillion-parameter system demands substantial compute resources to operate.

Pricing and Availability

Opus 5 is available now via API at $5 per million input tokens and $25 per million output tokens. (Tokens are the basic unit of information an AI model processes in both input and output.) A Fast mode running at roughly 2.5 times the default speed is also available at twice the base price—$10 per million input tokens and $50 per million output.

The release may alleviate ongoing concerns about Fable 5's limited public availability. Opus 5 is also accessible via subscription for all users.