import arcpy
from arcpy import env
from arcpy import mapping
arcpy.env.overwriteOutput = True
# Set Local Variable
A = "CUPS" #Layer you want to updat acres
mxd = arcpy.mapping.MapDocument("CURRENT")
# Create attribute called Acres
try:
if arcpy.Exists(A):
arcpy.AddField_management(A, "Acres", "DOUBLE")
print "Acres Attribute Added"
else:
print "Acres Field Not Added"
except arcpy.ExecuteError:
print "Error Occured Add Acres Attribute Failed"
print (arcpy.GetMessages(2))
# Create curser to update acres field
cur = arcpy.UpdateCursor(A)
# Pass through each row to update acres value
try:
if arcpy.Exists(A):
for row in cur:
row.Acres = row.Shape_Area /43560
cur.updateRow(row)
print "Acres Updated"
else:
print "Acres Not Updated Feature Class Does Not Exist"
except arcpy.ExecuteError:
print "Error Occured Update Failed"
print (arcpy.GetMessages(2))
del cur, row
arcpy.RefreshActiveView()
arcpy.RefreshTOC()
# Delete cursor and objects
del arcpy, env, A, mxd
!shape.area@acres!
It's documented in many different places - this is probably your best bet:
Using the Calculate Field tool
Geodata » Data types » Tables
http://resources.arcgis.com/en/help/main/10.2/index.html#//005s00000029000000