Wikipedia:WikiProject Geographical coordinates/dim:

The dim: parameter defines the diameter of a viewing circle centered on the coordinates. While the default unit of measurement is metres, the km suffix may be appended to indicate kilometres. The dim: parameter overrides the scale implied by any type: parameter.

Syntax — dim:<width><units>

width — integer number of metres (m) or kilometres (km)

units — m or km, if not specified, defaults to m

GeoHack uses dim: to select a map scale such that the viewing circle appears roughly 10 centimetres (4 in) in diameter on a 72 dpi computer monitor. If no dim:, type:, or scale: parameters are provided, GeoHack uses its default viewing circle of 30 kilometres (19 mi).

Samples

Subject	Dim	Markup	Result
Buckingham Palace	120m	{{coord|51.501|-0.142|dim:120m}}	51.501°N 0.142°W / 51.501; -0.142
London	10km	{{coord|51.507222|-0.1275|dim:10km}}	51.507222°N 0.1275°W / 51.507222; -0.1275
Western Hemisphere	10,000 kilometres (6,200 mi)	{{coord|0|N|90|W|dim:10000km}}	0°N 90°W
Ohio	400 kilometres (250 mi)	{{coord|40.5|-82.5|dim:400km}}	40.5°N 82.5°W / 40.5; -82.5
Dresden	20,000 metres (12 mi)	{{coord|51.03|13.73|dim:20000}}	51.03°N 13.73°E / 51.03; 13.73
Statue of Liberty	100 metres (330 ft)	{{coord|40.6892|-74.0445|dim:100}}	40.6892°N 74.0445°W / 40.6892; -74.0445