- Size of the tub
Aside from the obvious point, that this is important in checking how the bathtub will fit the designated space, this also needs to be considered for other reasons. Should you go for a one-person or two-person bathtub? Remember that if you choose a two-person tub, this will consume more water than a one-person tub.

The bathtub size is also interdependent with the capacity of the water heater. A bathtub usually requires 65% hot water. For some bathtubs, the hot water content may require up to 40 gallons. Consider then if after dispensing 40 gallons of hot water, will your water heater still have sufficient hot water for the rest of the household, or will it have enough time to reheat some water for consumption.

In this case, you may have to choose a smaller bathtub or upgrade your water heater so it will be able to supply enough water for a bigger bathtub. Another option is to install an instant water heater to the water source leading to the bathtub.
Also make sure that, with the bathtub's size, you get enough support for your head, neck and back.

-Material

Choosing the material for your bathtub depends on several factors: on how often you will use the tub, durability, ease of maintenance and budget.

Fiberglass is a cost-effective material, however, it doesn't have the durability of acrylic or porcelain bathtubs. Wooden and marble tubs are good-looking but these require much maintenance and may not last long. Cast iron tubs are the most durable, although these cost a little more than other materials.

-Depth

The bathtub's depth is important if you are considering using the bathtub for therapeutics. Many people enjoy soaking in a warm bath to rejuvenate the lost energy and to ease the pain in tired muscles. Soaking in a tub even reduces the stress levels that most people resort to a warm bath before going to bed.

However, few people know that there are special tubs designed for this purpose. Soaking tubs are designed to allow a person to immerse the whole body with comfort unlike that with a standard tub that is only designed to soak the lower part of the body.

-Functionality

Tubs with jets, such as whirlpool tubs, look very enticing, but will you be using the jets often? Consider the importance of the additional features and how will these features impact your power and water consumption.

- Features for the handicap and the elderly

People with handicap and the elderly rarely use the standard bathtub due to risks for additional injury. Check bathtubs that have features that allow easy entry and exit from the tub. These tubs also have grab rails and grab bars to prevent accidents while soaking in the bathtub. Check for ADA compliance if you want these features for your bathtub.

-Design

Most bathtubs come in cream and white, but are also available in other colors such as brown, maroon, pink, green and blue. Shapes are usually rectangle, oval, and round, but heart-shaped designs and corner styles are also offered.
These are important so the bathtub will match the color and the design of the bathroom. It also makes the bathtub inviting and makes soaking a comfortable experience.