Claude Opus 5 is a frontier model from Anthropic, released July 24, 2026 as the successor to Claude Opus 4.8 in the Opus line, which runs Opus 4.5 (Nov 2025) → 4.6 (Feb 2026) → 4.7 (Apr 2026) → 4.8 (May 2026) → Opus 5. It was Anthropic's fourth model release in under two months, following Opus 4.8, Fable 5 and Mythos 5. Anthropic held pricing at the Opus 4.8 level of $5 per million input tokens and $25 per million output tokens, half of Fable 5's input price, and made Opus 5 the default model on Claude Max (Source: anthropic.com; techcrunch.com).
| Field | Value | |
|---|---|---|
| Developer | [[companies/anthropic | Anthropic]] |
| Released | July 24, 2026 | |
| Parameters | Undisclosed | |
| Open weights | No | |
| Pricing | $5 / $25 per million input / output tokens | |
| Predecessor | [[models/claude-opus-4-8 | Claude Opus 4.8]] |
Capabilities and benchmarks
Anthropic reported the following results at release:
- Frontier-Bench v0.1: more than double Opus 4.8's score.
- CursorBench 3.2: within 0.5% of Fable 5's peak score, at half the cost per task.
- ARC-AGI 3: three times the score of the next-best model. Anthropic's reported figure is 30.2%; OpenAI reported on July 29, 2026 that GPT-5.6 Sol reaches 38.3% on the public set when retained reasoning and compaction are enabled through its Responses API, against 7.8% on the leaderboard configuration (Source: openai.com; the-decoder.com).
(Source: anthropic.com; fortune.com)
The system card reports an ECI point estimate of 162.1, slightly above Fable 5 at 161, and an ArtificialAnalysis score of 61 (Source: anthropic.com; thezvi.substack.com). See AI Benchmarks and Evaluation.
Opus 5 introduced a per-request effort setting that trades cost against capability, letting a caller select how much computation the model spends on a given request (Source: fortune.com).
Reported Frontier-Bench v0.1 scores place Opus 5 at 43.3%, Fable 5 at 33.7%, and Opus 4.8 at 18.7% (Source: qz.com). Anthropic claimed state-of-the-art results on both Frontier-Bench and GDPval-AA at announcement (Source: anthropic.com).
Safety and evaluations
Anthropic stated that Opus 5 scored 2.3 on its automated behavioral audit for overall misaligned behavior, which it described as the lowest of its recent models. It also stated that the model remains behind Mythos 5 on biology research and offensive cyber exploitation, and that Opus 5's cyber classifiers are expected to intervene roughly 85% less often than Fable 5's, with flagged requests falling back to Opus 4.8 — the same fallback arrangement used for Fable 5's diverted queries (Source: anthropic.com).
The system card reports several adversarial-robustness figures against Opus 4.8:
| Measure | Opus 4.8 | Opus 5 |
|---|---|---|
| Prompt-injection attacker success within 15 attempts | 5.5% | 2.0% |
| Computer-use attack success (with extended thinking) | 7.14% | 0.54% |
| Safety-classifier trigger rate on FrontierBench | 42% | 5% |
(Source: anthropic.com; thezvi.substack.com) See Prompt Injection.
The card also reports that the UK AI Security Institute judged Opus 5 "similarly capable" to Mythos Preview and Mythos 5 at attacking small, weakly secured enterprise networks, and that Opus 5 compromised safety research in 0.1% of cases against 13.6% for Mythos (Source: thezvi.substack.com). See AI and Cybersecurity.
Availability and pricing
Opus 5 was made the default model on Claude Max at release. Standard pricing is $5 per million input tokens and $25 per million output tokens, unchanged from Opus 4.8 and half the input price of Fable 5, which is priced at $10/$50 (Source: anthropic.com; techcrunch.com).
Reception
Reviewing the system card on July 25, 2026, Zvi Mowshowitz disputed the framing of Opus 5 as Anthropic's most aligned model, arguing that it conflates benchmark scores with alignment (Source: thezvi.substack.com).
Peer developers commented on the price-performance ratio. Cursor co-founder Sualeh Asif said the model "delivers near Fable 5 intelligence at Opus speed and cost," and Cognition CEO Scott Wu said it "approaches Fable-level performance at half the cost" on FrontierCode 1.1 (Source: qz.com).
Related models
- Claude Opus 4.8 (immediate predecessor; also the safeguard-fallback model for Opus 5's flagged cyber requests)
- Claude Fable 5 and Claude Mythos 5 (Mythos-class models released June 9, 2026)
- Claude Mythos Preview (cyber-capability comparator in the UK AISI assessment)
Relationships
- developed-by: Anthropic
- supersedes: Claude Opus 4.8
- depends-on: AI Benchmarks and Evaluation
- related: AI and Cybersecurity, Prompt Injection