Anthropic introduces the Claude Sonnet 5 model that offers performance close to Opus 4.8, but at lower prices

Recently, Anthropic has introduced its latest Sonnet model, Claude Sonnet 5. This model can make plans, use tools like browsers and terminals, and run autonomously at a level that required larger and more expensive models.

Introducing Claude Sonnet 5, our most agentic Sonnet yet.

It makes plans, uses tools like browsers and terminals, and runs autonomously at a level that just a few months ago required larger and more expensive models. pic.twitter.com/UKK8G7ww5h

— Claude (@claudeai) June 30, 2026

Claude Sonnet 5

If we talk about performance, the performance of this new model is said to be close to that of Opus 4.8, but at lower prices. It shows substantial improvement over its predecessor (Sonnet 4.6) on important aspects of agentic performance like reasoning, tool use, coding and knowledge work.

It is revealed that Sonnet 5 shows an overall lower rate of undesirable behaviours than Sonnet 4.6, and is generally safer to use in agentic contexts. Sonnet 5 also has lower ability to perform cybersecurity tasks than current Opus models.

While comparing and testing the Sonnet 5 model, it was discovered that it provides substantially improved cost efficiency at medium effort; its higher-effort performance can match Opus 4.8 on some tasks. During the early access period, it was found that the Sonnet 5 is much more agentic than its predecessors.

On agentic safety, the model is better at refusing malicious requests and resisting hijack attempts in prompt injection attacks. The model shows a lower rate of hallucination and sycophancy than Sonnet 4.6. On Anthropic’s automated behavioural audit, which tests a wide range of misaligned behaviours such as cooperation with misuse and deception, Sonnet 5 scored lower overall. However, it did show somewhat higher rates of misaligned behaviour on this assessment compared to the more capable Opus 4.8 and Claude Mythos Preview.

The Sonnet 5 model is not trained for cybersecurity tasks and showed poorer performance than Opus 4.8 and Mythos 5 when the company tested the models for developing software exploits. The model is launched with cyber safeguards enabled by default.

These safeguards, which detect and block dangerous cyber usage in real time, are the same as those present in Opus 4.7 and 4.8.

Availability

Claude Sonnet 5 is available across all plans: it is the default model for Free and Pro Plans, and is available to Max, Team and Enterprise users. It’s also available in Claude Code and on the Claude Platform, where it launches with introductory pricing of $2 per million input tokens and $10 per million output tokens through August 31, 2026, after which it will be priced at $3 per million input tokens and $15 per million output tokens. Developers can use claude-sonnet-5 via the Claude API.

The company has also increased limits across Chat, Cowork, Claude Code, and the Claude Platform to accommodate the higher token usage of higher effort levels; users can select whichever level makes sense for their particular project.