If you want to find out the distance between two places on a map, you can use the scale of the map. It may be presented either as a bar scale or a ratio.

To use a bar scale, you need the help of a ruler. If the bar is 5 centimeters long and contains the number 100 km, 5 cm on the map represents 100 km in the real world, meaning that 1 cm is 20 km.

The scale can also be presented as a ratio. The ratio shows the relation between a centimeter on the map and a centimeter in the real world. For example, if the scale of the map is 1 : 250 000, 1 cm on the map represents 250 000 cm in the real world. When you convert this number to kilometers, you will see that 1 cm on the map represents 2,5 km in the real world.

The distance between San Francisco and New York is 8 cm on the map. The scale is 1:50 million. This means that one centimeter on the map represents 50 million centimeters or 500 kilometers. The distance between the two cities is therefore 8 x 500 km= 4 000 km.