Soaking tubs have become increasingly popular in recent years, and one of the reasons for this is their compact dimensions. Featuring a shorter width and length than conventional baths, they can be installed in smaller bathrooms and they offer a much wider range of layout options.

Often, when people plan a bathroom redesign, they are most concerned with the length of the bath because it’s generally the longest dimension that determines where and how it will fit. However soaking tub width is also very important and it’s a consideration that should not be overlooked. In this article, we’ll explain why.

Soaking Tub Width and Layout Options

In a small bathroom, the layout choices may be limited. As we explain in our post about ‘Small Bathroom Ideas’ a short bath can often be installed lengthways across the end of a bathroom to create more free space in the rest of the room. In such instances, the tub’s width will make only a nominal difference. However, if the owner wants to install the soaking tub along one of the other walls, a narrower bath can make an appreciable difference to the usability of the room – especially if there are doorways and other fixtures such as WCs and basins to consider. Often, a wider soaking tub will constrain the layout options.

Soaking tub, New York USA. The Calyx in the new bathroom in Brookhaven.

Above: In this example, taken from one of our customer reviews, a wider soaking tub would not have fitted in the available space.

When it comes to layout and installation, it is the external length and width of a soaking tub that really matters. However, a soaking tub’s internal width is also very important, as we explain below.

Bath Width and Energy Efficiency

The amount of energy it takes to heat a bath depends mostly upon how much water it contains. In this respect, soaking tubs generally have an advantage over more traditionally shaped baths, but the benefits can be eroded if a soaking tub is made too wide or long.

It’s important to remember that a soaking tub needs only to be wide enough to be comfortable; enough to allow the upper back and shoulders to spread and relax. Any empty space to either side of the body is effectively wasted: it leaves more of a void to fill and, consequently, it means higher costs for both water and heating.

For this reason, a well-designed, single-person soaking tub will typically have an internal width of between 550mm and 700mm. Slightly wider models may suit users with a particularly large frame but, more often than not, a soaking tub’s width need not exceed 700mm (27.5 inches).

Soaking Tub Widths (Cabuchon Models)

To illustrate this, the following list shows the external dimensions of our most popular single-seat soaking tubs, followed by their internal widths.

  • Calyx 1230: 1230 x 815mm (ext) and 675mm (internal width)
  • Calyx 1440: 1440 x 850mm (ext) and 710mm (internal width)
  • Imersa (Standard): 1220mm x 865mm (ext) and 645mm (internal width)
  • Imersa (Large): 1370mm x 865mm (ext) and 645mm (internal width)
  • Nirvana: 1372 x 860mm (ext) and 550mm (internal width)
  • Takara: 1372 x 860mm (ext) and 630mm (internal width)
  • Yasahiro 1440 x 850mm (ext) and 640mm (internal width)

Note that the difference between external width and internal width is determined by the thickness and angle of the bath’s side walls. A soaking tub’s internal width is generally measured close to the top, where the bather’s shoulders would normally contact the back of the bath.

Bespoke Modifications to External Dimensions

The dimensions of the products listed above refer to our standard bath models. However, we can alter bath rim sizes to some extent in order to ensure a snug fit into alcoves and other small spaces. In terms of external dimensions, this means we can adjust a soaking tub’s width and length, while leaving the internal dimensions unchanged.

Minimum Bath Sizes

The smallest bath size among our standard bathtub models is 1230mm x 815mm, but these external dimensions can be reduced somewhat by modifying the rims. Taking up to 40mm off the width of each rim could reduce the smallest bath dimensions to 1155mm x 755mm, although this is an absolute minimum. Moreover, it should be noted that this reduced size would impose some limitations on the installation options. For example, with much smaller rims, brassware would have to be mounted elsewhere, such as on a wall or an accompanying deck, and a notch may have to be created in the wall to accommodate the overflow. However, none of these modifications would affect the internal width of the soaking tub.

Soaking Tub Width and Hydrotherapy

Deep soaking tubs make excellent hydrotherapy baths (also known as spa bath tubs), as we have pointed out in many previous posts. (Example: Deep Soaking Tubs and Hydrotherapy – Convergent Technologies.) One reason for this is that the close-set, steep-sided walls ensure that the hydrotherapy nozzles are positioned very close to the bather’s body. The nearer they are, the more they are able to transfer heat and pressure to the muscles that need it. Conversely, if they are set further away, their effects can be reduced due to general dispersal in the water.

A good hydrotherapy bath will often have jets set into the side walls and, for these reasons, a narrower spa bath tub will tend to work more effectively than a wide one.

Interior of a hydrotherapy bath showing the placement of jets for the back and legs.

Above: The soaking tub width will determine the distance between the bather’s muscles and any nozzles in the side walls. A closer-fitting spa bath tub will tend to work more effectively than a wider one.

Find Out More

If you are planning a bathroom refurbishment and you have a question about the dimensions of your preferred soaking tub, please get in touch.

Please also note that soaking tub widths, lengths and depths are all listed in our technical data sheets, which can be downloaded from individual product pages or from our Resources page. Measurements are listed in both Imperial and Metric.