Bathroom stalls and bath/shower combinations are available in a variety of standard sizes and styles. Most homes are built using standard sizes because they are easier to find and are less expensive, but more expensive homes may have a custom shower in a non-standard size. Make sure you know the correct measurements of your space before purchasing.
A combination shower/bathtub is the most common type of shower found in residential buildings. Most bathtubs are of standard width and length, while basin depth varies greatly. Built-in bathtub standard sizes range from 30-40 inches wide, 60-70 inches long and 16-24 inches deep. Freestanding tubs and claw foot tubs are often decorative because they typically sit in an open area. Basin size is similar to built-in tubs, but they are rounder and much deeper.
Shower stalls are often used in smaller or second bathrooms. They may be square, rectangular or built to fit into a corner. The most common widths are 36, 32 and 60 inches, respectively with lengths varying from 22-80 inches. Accurately measure your space when searching for a shower stall; there will be an option to fit into nearly any spot. Measure each angle twice for accuracy.
Tub surround styles vary widely, and although there are a few standard sizes, many are modular. Modular surrounds feature two or more panels, allowing you flexibility and the ability to cover a non-standard sized area without ordering a custom surround. The most common dimensions are 60 inches by 30-32 inches. Most are constructed with a sturdy composite material covered in acrylic which allows for easier cleaning and maintenance, and for you to cut the surround to the correct size with a utility knife.
Custom showers are typically built-in and covered in tile, and are often made to fit the space available. Sizes are not standard, as concrete and tile can be laid in any configuration and plumbing installed to fit any location. If you have a built-in or otherwise custom shower that needs replacing, you'll need to either stick with the existing materials or hire a contractor to alter the space. If you're installing a new shower in a location that doesn't allow for standard sizes, a custom shower might be the way to go.