Parser: Python Expression: !shape.area@acres!
I've used the methods you have described, first using the python expression !shape.area@acres! and using the calculate geometry function in ArcMap 10. I set the precision and scale to 0. I get slightly different acreage amounts. Not a big deal unless I am calculating small parcels or I'm figuring acreage for $ cost. Has anyone come across this discrepancy or am I doing something wrong?