The softball diamond is closely related to the baseball diamond, which is one of the oldest and most complex pieces of geometric symmetry in all of sports. Of course, not every field is constructed exactly the same. Fields all across the world differ in terms of distances of baselines, outfield fences, and the pitching rubber.
In the official rules of the International Softball Federation, the maximum outfield distance is stated to be 250 feet. Interestingly, this maximum is shared by both men and women. The variations in the distances are purely team-specific. While men’s fields tend to be deeper, youth leagues and collegiate teams often have smaller outfields. These dimensions can also vary depending on the league.
The following are all taken from the official International Softball Federation rules, but apply universally to nearly every full-sized field in the world.

Home Plate Area

    Home plate: The plate is a white rubber pentagon with one side measuring 17 inches in length from the base to the point. Two sides measure 8.5 inches in length, and two sides measure 12 inches in length. The two 12-inch sides form a point and face directly away from the pitcher’s rubber.
    Batter’s boxes: Both the right-hand and left-hand boxes measure 3 feet in width and 7 feet in length; each box is 6 inches away from home plate, positioned so the midpoints correspond to the midpoint of home plate.
    Catcher's box: The catcher’s box measures 10 feet in length from the back of home plate, and 8.5 feet in width.

Pitcher’s Mound Area
    Pitcher's rubber: The rubber is a white slab, measuring 24 inches by 6 inches. The pitching rubber should be level with the ground.
    Pitcher's circle: The pitcher’s circle should be a measurement of an 8-feet radius around the pitcher’s rubber.

Read more at: http://softball.isport.com/softball-guides/softball-field-dimensions