Geodiversity, as diversity of the abiotic environment, includes terrain ruggedness (or roughness), which is one of the essential parts of geodiversity evaluation. The terrain ruggedness index (R) represents the value of one of the main geodiversity components. The purpose of the study is to discuss the characteristics of R in the scope of geodiversity, and to show how R differs within two specific study areas if we study them using a data scale that covers both areas and only site-specific data. Hence, the main methods include geodiversity element mapping, calculating R based on either the study area or broader-scale data and discussing the differences that arise. The findings show that R should not be calculated only within individual study areas if the results among different study areas are to be compared; rather, it should first be calculated on a larger scale for the whole region in which we are about to compare the specific study areas. The applied value of these results is that such data are then suitable for calculating the geodiversity index (G) according to specific methodological steps and for further analyses.