A scale is either a device used for measurement of weights, 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.

• The Richter scale, the Mercalli scale, the Rossi-Forel scale and the Omori are all used to measure the intensity of earthquakes.
• The Beaufort scale is used to measure wind force.
• The Celsius scale measures the temperature.
• The Goldberg scale measures mania and depression.
• The Scoville Scale measures the hotness of peppers.
• The Glasgow Coma Scale measures the severity of comas.
• The Fujita scale measures the intensity of tornadoes.
• The Torino scale and the Palermo scale measure the impact hazard level of near-Earth objects such as asteroids.

See also

• Orders of magnitude
• Weighing scale
• Scale (disambiguation)
• Scale (social sciences)
• Scales of scale models