Bonsai 27B is a 1-bit large language model (LLM) that can run on a phone, with a size of 3.9GB. It is available in 1-bit and ternary variants and brings multi-step reasoning, tool calling, and multimodal understanding to local devices. The model is designed to be efficient and can process many operations with a single instruction. Bonsai 27B is part of a larger effort to create more efficient LLMs that can run on smaller devices.