Measuring length is an integrative part of everyday life. Understanding the procedure of measuring length contributes to the conceptual understanding of measurement, which includes measuring area and volume. Measuring, and thus measuring length, is one of the terms that connects mathematics not only with everyday life, but also with other mathematical areas such as geometry, numbers, statistics, etc. The importance of understanding and developing the concept of measuring length is evidenced by the fact that it is an integral and very important part of many curricula related to preschool education. Of course, measuring length at preschool age implies processes, strategies and measuring instruments that are adapted to the developmental level of children that age. The paper presents the theoretical and methodological foundations of length measurement, development theory of length measurement, as well as a systematic review of length measurement strategies used in preschool age.