A statement of scale is typically used on a map. The statement of scale defines a ratio or relationship between a unit of length on the map and the piece of Earth being referenced in the map.
According to the Intergovernmental Committee on Surveying and Mapping, scale defines a mathematical relationship between a map's size and the size of the piece of Earth that is being described. A statement of scale used as an example is 1:100,000, which means that every one unit on the map corresponds to 100,000 units on the Earth. For example, one centimeter on the map equals 100,000 centimeters, or one kilometer, on the Earth.
According to Science Encyclopedia, a statement of scale may also use a verbal relationship rather than a numeric ratio. For example, a map may show a verbal relationship of "one inch equals one mile" for its scale rather than providing a numeric ratio of 1 inch:63,360 inches to reflect the same. There are 63,360 inches in a mile.