# Claude Sonnet 5.5 puts AI efficiency in focus again > Source: > Published: 2026-09-28 19:25:15+00:00 Anthropic is releasing a more cost-effective version of its flagship version 5.5 model. On Monday, the AI lab released Claude Sonnet 5.5, the latest addition to its lineup, a "lower-cost complement" to its recently-released Opus 5.5 model featuring faster performance compared to previous iterations. The company said that Sonnet 5.5 runs 30% faster than Claude Sonnet 5. Notably, however, Anthropic says that Sonnet 5.5 needs far fewer tokens to do the same amount of work as previous models, costing up to 30% less for most tasks. On the surface, Sonnet 5.5 costs the same as its previous generation, sitting at $2 per million input tokens and $10 per million output tokens, as well as 20 cents per million cache reads. For reference, [OpenAI's GPT-6 Sol](https://openai.com/index/introducing-gpt-6-sol-and-luna/) runs at the same cost of $2 per million input tokens and $10 per million output tokens, and [Anthropic's Opus 5.5 costs double](https://www.thedeepview.com/articles/opus-5-5-makes-frontier-ai-cheaper-and-safer), at $4 per million input tokens and $20 per million output tokens. Sol and Opus are considered the same class of model, while Sonnet is in the same class as OpenAI's mid-tier Terra model. Sonnet performs strongest in everyday tasks, such as fixing bugs and creating documents, slides and spreadsheets. Compared to the previous generation of Sonnet, Anthropic said Sonnet 5.5 offers a number of improvements: - The model sweeps Sonnet 5 across the board in all benchmarks, including agentic coding, knowledge work, computer use and multidisciplinary reasoning. Though it sits just below Opus 5.5's scores in almost every benchmark, Sonnet 5.5 scored higher than both Sonnet 5 and Opus 5.5 on the Terminal-Bench 4.0 benchmark for agentic coding. - Anthropic says the model writes more clearly than previous iterations, making it a better partner for collaborative work, and is faster on less complex tasks. - Sonnet 5.5 improves or meets Sonnet 5 on most measures for alignment in Anthropic's automated behavioral audit, the company said. Sonnet 5.5's cyber capabilities are comparable to those of Opus 5, making it the first of the Sonnet series to have the same cyber safeguards as its most capable models. In addition to cybersecurity safeguards, Sonnet 5.5 is built with guardrails against the harmful queries for biology. Additionally, Sonnet 5.5 is built to prevent model distillation attacks, launching with "safety classifiers" that prevent reasoning extraction and "preserved thinking" that prevents the model's reasoning from being "decoupled from the account that created it." Claude Sonnet 5.5 is available on all platforms, and with no data retention. Anthropic also reported that it will be releasing a 5.5 version of Claude Haiku, the lightest and lowest-cost model series it offers, in the coming weeks. ## Our Deeper *View* OpenAI and Anthropic have read the room on enterprise cost cutting. They are now competing heavily on price, pushing the boundaries on just how cheap they can serve up intelligence while leapfrogging each other on performance. The problem that the labs face, however, is that they are relying on conventional model architecture to try and drive down the efficiency curve. Meanwhile, neolabs may present a threat to that strategy, as companies like [Jev-maker Typesafe](https://www.thedeepview.com/articles/jev-puts-frontier-ai-price-premium-under-pressure) and [Pathway](https://www.thedeepview.com/articles/pathway-breakthrough-challenges-ai-economics) gain traction as they look towards a future beyond traditional LLMs that can provide comparable performance at a fraction of the cost.