Map scale

Map scale expresses the relationship between a distance measured on a map and the corresponding distance on the ground. It may be shown as a ratio, a written statement, or a graphic bar.

Representative fraction: A scale written as a ratio between map distance and corresponding ground distance in the same units. This ratio states map scale numerically without depending on a particular unit.
Large-scale map: A map showing a relatively small area with comparatively fine detail. Its larger representative fraction means a given ground feature occupies more map space.
Map projection: A mathematical transformation that represents Earth's curved surface on a flat map. Projection distortion can make the stated scale vary across a map.
Map extent: The geographic area represented within a map's boundaries. Extent describes how much territory appears, while scale describes its size relative to the map.
Graphic scale: A line or bar on a map marked to show equivalent ground distances. Its marks show map scale visually and remain useful when the map is resized.
Small-scale map: A map showing a relatively large area with comparatively limited detail. Its smaller representative fraction compresses extensive ground areas into little map space.
Scale factor: A multiplier relating one measured quantity to another, often expressed as a ratio. The representative fraction is a scale factor between map and ground lengths.
Map resolution: The smallest spatial detail distinguishable in a mapped dataset or image. Resolution concerns detectable detail, not the ratio between map and ground distances.
Verbal scale: A written statement relating a map distance to a ground distance, such as one centimeter to one kilometer. This form expresses map scale in familiar units.
Cartographic generalization: The selection, simplification, and displacement of map features to make them legible at a chosen scale. As scale decreases, generalization controls which features remain visible.

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