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I have a shapefile with building footprint outlines. I am trying to identify buildings that are a certain size in meters squared. The shapefile that I has, has a SHAPE_Area column, but I cannot tell what unit it is.

How can I tell what the units currently are?

The CRS for this layer is EPSG:2260, NAD83 /New York East (ftUS).

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  • What UTM zone are you in? Oct 23, 2018 at 15:33
  • It should be 18N
    – Laura
    Oct 23, 2018 at 15:46
  • The shape_area column of your data is out of sync with the polygons since it left the ArcGIS system it once lived in. You can export/save your shapefile to a new file while doing so, re-project the coordinate system to EPSG:32618 (which is UTM zone 18N). From there, do an updated $area calculation on your shape_area field, and you should have units in metres... Oct 23, 2018 at 15:56

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I created a building footprint for one aleatory selection on map at East Hampton (New York). The CRS for this layer is EPSG:2260, NAD83 /New York East (ftUS). Afterward, I created 'SHAPE_area' field and calculated its corresponding area by using field calculator (geometry section). Despite CRS is expressed in feet, area was determined in square meters by default. So, it was also calculated area in square feet ('area_ft2' field) multiplying 'SHAPE_area' field by 10.764.

At following image it can be observed approximate area determined with Measure Area Tool of QGIS (square feet). In your case, compare result with value in 'SHAPE_area' field for one arbitrary record. If it coincides, units are in square feet. So, use 10.7639 as dividing conversion factor to get your new field in square meters.

If it doesn't coincide, use Measure Area Tool of QGIS in square meters for verifying field area values.

enter image description here

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