A tool commonly used to measure distance on a map is a scale ruler or a map measurer. A scale ruler is marked with divisions that represent real-world distances according to the specific scale of the map, such as 1:50,000 or 1:100,000. To use it, one aligns the ruler along the route of interest to get the distance. Alternatively, a map measurer is a specialized tool resembling a small wheel that can easily roll along the map's surface, providing distance calculations in both miles and kilometers. Both tools are essential for geographic navigation and planning.