Mowers usually vary between 20 to 24 inches in breadth, but the kind of size people usually prefer on the area of the ground. According to a rule of thumb, a cutting width of 110 cm or 42 inches could cut grasses of an area of 4000-meter square which is round about 1 acre and 16-20Horsepower of the engine and an area worth 4000-meter square needs cutting width of about 48 inches or 120com which would be needing 20 to 24 Horsepower engine.