Abstract: Through a study on the use of the traditional construction ruler (yingzaochi) in regional building practice, the paper highlights the difference in standard ruler-length between northern and southern China. The paper then discusses the regional distribution and length range of the most common ruler types (referred to as “vernacular rulers” or xiangchi), such as the Lushigong chi, Wu chi, Zhe chi, Min chi, Huai chi, Gan chi, and Yue chi. Lastly, the paper identifies several historical factors that led to the formation of different “vernacular rulers”.