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I have a map in the WGS84 (EPS:4326) coordinate system and I am putting a scale bar on the map with Scalebar units of Feet and label in miles.

When I select Feet from the Scalebar units dropdown menu, the automatically selected Label unit multiplier is 5419.95 and the Label for units is miles.

There are 5280 feet in a mile, not 5419.95.

Why does QGIS automatically use this value when feet is selected (and miles is automatically filled in for the label)?

Note that if I change to a different coordinate system (e.g. NAD83), the 5419.95 conversion remains.

EP_Guy
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    Possible duplicate of Problems with scale bar units in qgis composer – Chris W Dec 14 '15 at 04:13
  • I am running QGIS 2.12.1 and although WGS84 (units in degrees) affects the grid frame of the map, QGIS appears to be creating a correct scalebar when I choose feet with a unit conversion of 5280. That is, when I choose 1 mile = 5280 feet, the scalebar roughly corresponds to 1 mile on the map. If it were using degrees, the scalebar would be obviously wrong. – EP_Guy Dec 14 '15 at 04:52
  • The point isn't the units the scalebar is using (I'm not suggesting it's using degrees), but the fact there is no direct conversion between degrees and feet/miles. It somewhat depends on how large an area your map covers and where that area is, but the number of miles in a degree varies. The suggestion is to use a projected coordinate system, not a geographic one (NAD83 is still geographic). This issue is a level above the actual unit conversion between feet and miles. – Chris W Dec 19 '15 at 18:32

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