Harvest the wheat crop.
Determine the exact poundage of the wheat crop you've harvested. The grain elevator where the wheat is sold will do this.
Determine the acreage area from the field from which the wheat was harvested.
Divide the total poundage of wheat harvested by 60, as there are 60 pounds of wheat per bushel. This figure is the total number of bushels harvested.
Divide the number of bushels by the number of acres harvested. This figure is the bushels per acre yield number.