In ArcGIS, how do I add an area or perimeter field to a shapefile or feature class?
Typically, polygon feature classes in ArcGIS already have a length and area field defined. However, if you do not see this information reported in the attribute table, you can add a new field to an existing polygon feature class or shapefile. To create a new field containing values for each feature’s area, perimeter, or x and y coordinate of centroid: • Verify that the data layer has a coordinate system. In ArcMap, right-click the data layer and select Layer Properties, and then choose the Source tab. If the coordinate system is undefined, you will need to project the data before continuing. • Open the layer’s attribute table. Right-click the data layer and select Open Attribute Table. • In the attribute table, click Options and select Add field. ArcGIS allows you to add a new field only if you are not in an editing session. • Name the new field, specifying the field type as either float or double, according to your needs. A new field is added with null values for each feature. • Begin
