# Anthropic upgrades Claude with new Sonnet 5.5 model, details here > Source: > Published: 2026-09-28 18:07:55+00:00 Anthropic is upgrading Claude Sonnet, replacing Sonnet 5 from June with Sonnet 5.5 as the best medium-sized model. ## Claude Sonnet 5.5 upgrades Anthropic’s medium model Anthropic currently offers a few AI models under the Claude umbrella. The three main models are Haiku (smallest and cheapest), Sonnet (medium size and price), and Opus (largest and most expensive of the three). There’s also Fable/Mythos, which is even more capable and costly, which represents Anthropic’s highest tier. Today’s new Claude model follows the arrival of Opus 5.5 [last week](https://9to5mac.com/2026/09/22/anthropic-upgrades-claude-with-new-opus-5-5-model-details-here/). Anthropic promised to upgrade Sonnet and Haiku “in the coming weeks” at the time. Anthropic says Sonnet 5.5 is strongest at everyday tasks with a clear scope, including fixing bugs and creating polished documents, slides, and spreadsheets. The company also highlights its design capabilities, from refining user interfaces to producing slides that follow templates and need minimal editing. Early testers described it as a better collaborator than Sonnet 5, Anthropic says, with clearer writing and speed suited to quick iteration on less complex tasks. Sonnet 5.5 keeps Sonnet 5’s pricing: $2 per million input tokens, $10 per million output tokens, and $0.20 per million cache reads. Anthropic says it typically uses far fewer tokens to complete the same work, while generating output more than 30% faster than Sonnet 5, making it the fastest Sonnet model to date. With cybersecurity capabilities comparable to Opus 5, Sonnet 5.5 is the first Sonnet model to launch with cyber safeguards and fallbacks similar to those used for Anthropic’s most capable models. Its biology safeguards remain unchanged from Sonnet 5. Anthropic says both target a narrow set of high-risk requests, leaving routine software development and most life sciences work unaffected. You can read the full announcement post [here](https://www.anthropic.com/claude-sonnet-5-5). **Do more with your Apple products** [AirPods 5 | Apple’s newest wireless headphones](https://amzn.to/4hnE1jt) [Apple AirTag 2 | Add Find My tracking to keys, bags, bikes, more](https://amzn.to/4vjNWN1) [AirPods Pro 3 | Apple’s best wireless headphones](https://amzn.to/4ut3FYp) *FTC: We use income earning auto affiliate links.* [More.](https://9to5mac.com/about/#affiliate) [our homepage](http://9to5mac.com/)for all the latest news, and follow 9to5Mac on [exclusive stories](https://9to5mac.com/feature/exclusive/), [reviews](https://9to5mac.com/guides/review/), [how-tos](https://9to5mac.com/guides/how-to/), and [subscribe to our YouTube channel](https://www.youtube.com/9to5mac)