Maps show the layout of an area in a condensed format for the convenience of the user. Even if the map represents just of a small neighbourhood, every part of the neighbourhood must scaled down to fit on a single sheet of paper. The map scale lets you know by how much the distances have been scaled down so you can calculate the real-world distance between different points on the map. To do this, you need to know the distance on the map and the scale factor.
Use a ruler to measure the distance between the two points you are considering on the map.
Look up the scale factor of the map to determine how many units in the real world each unit on the map represents. For example, if the scale of the map is 1:1 million, 1 inch on the map would be equal to 1 million inches, or about 15.78 miles.
Multiply the distance you measured on the map in Step 1 by the scale factor in Step 2. For example, if you measured a distance of 3 inches on the map and the scale factor was 1:1 million, you would multiply 3 by 1 million to find that the actual distance is 3 million inches, or about 47.35 miles.