A shower base is the bottom floor of your shower stall. Usually this part is about 5 inches high with a drain hole and made to fit right inside the walls of your showering area. A few standard sizes are common for shower bases; however, any size is available for custom fabrication.
Standard Full Size
A standard full-size shower base is usually 30 inches wide and 60 inches long. This size shower base fits into any typical, standard home bath or shower area with few modifications required to the surrounding shower walls. As always, furring strips, which are long strips of wood that act like shims, may be used to fit shower bases into areas that are not perfectly square.
Larger Full Size
Some showering areas are larger than others. In large full-size showering areas, the dimensions extend up to 42 inches wide and 60 inches long. Mid-size bath and showering areas are 36 inches wide and 60 inches long. The additional width is available for those seeking larger whirlpool or jet tubs. Standard size shower bases built to these lengths will fit neatly into these predetermined spaces when a tub is not installed.
Square Shower Bases
Many shower bases are smaller than the full-size base made to fit into a space normally occupied by a tub. These showers are built into bathrooms with little space and may even take up space once occupied by a closet. Square shower bases are generally 32 to 48 inches square. The size depends on the shower surround and the space available in the bathroom. You'll find square shower bases, angled shower bases and even circular shower bases. Common sizes include 36 x 36 inches and 48 x 36 inches.
Rounded Shower Bases
Some shower bases are rounded at one end. This configuration makes sense in smaller bathrooms where space is at a premium. A square shower base takes up more space than a circular one, and since people don't typically use the corners of the shower as much, they do not add much in the way of comfort. Rounded shower bases are common sizes, ranging from 30 to 48 inches wide along the sides; on the last side, the base is arched. The measurement accounts for the width from the opposite side to the edge of the rounded side on the base.