How to Choose Contour Interval: A Quick Guide

Choosing the right contour interval is essential for creating clear, accurate, and easy-to-read maps. At NPLUS SOLUTIONS, we assist clients in selecting the most suitable contour intervals to achieve reliable results for their projects. A contour interval is the vertical distance between two contour lines on a map. If the interval is too small, the map becomes cluttered and hard to interpret; if it is too large, important terrain details may be missed. Choosing the correct interval allows for a balanced and practical representation. Several factors influence this choice. The type of terrain matters; for flat areas, small intervals ranging from 0.25 meters to 1 meter are ideal. In hilly regions, intervals of 2 to 5 meters are effective, and mountainous areas require intervals of 10 meters or more. The map scale also plays a role; large-scale maps need smaller intervals, and small-scale maps can use larger ones. The purpose of the survey is another factor — construction and engineering projects require small intervals for precision, while general mapping uses larger ones for simplicity. Lastly, data accuracy from DGPS, drones, or LiDAR technology supports the selection of smaller, more precise intervals. Choosing the right contour interval ensures better planning, visualization, and execution of land development or construction projects. At NPLUS SOLUTIONS, we provide expert contour mapping services and help you select the ideal contour interval based on your project’s needs.