A scale is either a weighing scale used for measurement of weight (mass or force), or a series of ratios against which different measurements can be compared. The latter need not always be a linear ratio, and is often logarithmic.
A draughtsman's scale is a ruler-like device, often with a triangular cross-section, that permits him to represent items in the same relative dimensions.
The scale of a map or enlarged or reduced model indicates the ratio between the distances on the map or model and the corresponding distances in reality or the original. E.g. a map of scale 1:50,000 shows a distance of 50,000 cm (=500 m) as 1 cm on a map, and a model on a scale 1:25 of a building with a height of 30 m has a model height of 1.20 m.
In model railways a number of standard scales are indicated by letters and numbers such as "G", "O", "HO", "N" and "Z".
Scales with special uses are often named after the person who invented them.
See also