Farmers in Western Canada are continually assessing where to invest their next dollar. In considering a farm expansion and the machinery assets they need to match their current farm size or a possible expansion. This study attempts to find the optimal farm size by creating a farm budget model that maximizes profit over a range of different farm sizes. As farm size increases there is more risk that inclement weather will lengthen the time needed for crop operations. Previous studies have shown that both seeding and harvest operations have optimum time windows in which they should occur for best yield results. The results of this research showed that net mean profit was maximized around a 9,000 acre grain farm. For farm sizes above 9,000 acres losses associated with lack of field operation time could not be compensated by cropping additional acres.