Key:sqkm

The sqkm=<number> key can be used to indicate the area covered by an object (in unit square kilometre = sqkm). E.g. place nodes or any huge object have no good way to calculate their size.

Whenever possible, it is recommended to also add the key source:sqkm=* to the same object.

Why this tag should be avoided

Although this tag has minor usage, in general, any property which can be derived from the geometry should never be tagged explicitly:

• The size of the object as mapped may be inaccurate and the size will change as the data is refined.
• The area of an object may change over time (glaciers, some lakes & seas, cities, buildings etc)
• Sources for areas such as Wikipedia are inadmissible on OSM.
• The actual concept being mapped may not be so well defined as to have an area which everyone can agree on (seas, bays etc).
• This type of tag violates the on-the-ground rule.
• For objects such as continents and oceans there is no agreed on size

Examples

• name=Europe
• sqkm=10180000
• place=continent
• source:sqkm=wikipedia

• natural=water
• sqkm=12.34
• source:sqkm=NHD
• water=lake