Anthropic releases Opus 5.5 at $20 per mTok

Anthropic launched its newest artificial intelligence model, Opus 5.5, on September 22, 2026. The company stated that the model sets a new standard in coding and knowledge work, outperforming the larger Fable model across several benchmarks and informal tasks.

The release lowers computing costs compared to its predecessor, Opus 5, which launched on July 24, 2026. Output tokens for Opus 5.5 are priced at $20 per million tokens (mTok), down from $25 per mTok previously. The model also operates faster and requires less compute power. In addition, Anthropic announced plans to release Sonnet 5.5 and Haiku 5.5 in the coming weeks.

Because its biology and cybersecurity capabilities match those of Mythos, Opus 5.5 includes the same safety safeguards as Fable. These restrictions limit tasks such as discovering software exploits in compiled code and developing biological weapons. Alignment testing and pre-release evaluations were conducted with outside groups including METR and Frontier Design.

Opus 5.5 is Anthropic's first release since CEO Dario Amodei announced a strategy to pace frontier capabilities alongside alignment progress, citing the need for greater prudence to ensure safety measures keep up.