How are you planting- are you broadcasting or row planting? Do you have a target population density?
Corn seed is typically sold in 80,000 count bags and most production farmers plant in the 30,000 to 35,000 seeds per acre population (but that is thru an actual planter) typically on a 30" row spacing. So if you are row planting a bag should get you 2.3 to 2.7 acres depending on the population rate. Also keep in mind that most corn seed isn't graded by shape and size anymore...so if you have an old-school plate planter you may need to do some trial and error to get things to work properly. I use an old 70's era plate planter and thought it's a simple machine...it can require some tinkering to get it to do what I want at times. I get a lot of doubles and don't control the row spacing real well, but it's deer food so I don't let it bother me.
I have no exp broadcasting corn.