How to Measure and Select a New Toilet

Toilet bowl in the bathroom
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Toilets are pretty trouble-free plumbing fixtures. Although the water-supply valves, flush valves, and wax ring that seals the toilet to the floor all may fail and need to be replaced from time to time, the porcelain or china fixture itself will likely remain in perfect operating shape unless the bowl or tank become cracked. 

Nevertheless, you may want to replace your toilet, either for purely aesthetic reasons, such as when remodeling a bathroom; or to take advantage of new water-saving features available on modern toilet designs.


Replacing a toilet yourself can seem like an intimidating job, but it's really fairly easy with a little study and planning beforehand. But before you get to that point, you need to know something about how to measure for a new toilet, and what kind of options you have when purchasing a replacement toilet. 

Taking Measurements

The first step is to measure carefully to ensure that the toilet you purchase will fit in the same location as the old one. Measuring is done with the old toilet in place.

Start by measuring from the wall behind the toilet to the center of the bolts at the base of the toilet. If your existing toilet has four bolts, measure to the center of the back bolts. This measurement is known as the rough-in measurement. For a standard toilet, the rough-in measurement should be between 11 inches and 13 inches. Keep this measurement handy when you go to purchase the replacement toilet.

If the rough-in measurement is not between 11 inches and 13 inches,  a standard toilet will not fit the space, and you will need to look for a toilet designed for that specific rough-in distance. Toilets designed for 10-inch are relatively common. They are often used in a very small bathroom where space is at a premium.

For smaller bathr ooms, it is also a good idea to measure the space surrounding the toilet. If you select a toilet with a different bowl shape, it may take up too much space and make it hard to move around the toilet. 

Researching Your Options

With measurements in hand, it's time to consider what options are available for your new toilet—and there are quite a few.

Type: The first option is between one-piece and two-piece models. With one-piece toilets, the tank and bowl are all one integral unit. These toilets look very sleek and have a low-profile, but they are generally a more costly than the typical two-piece toilets. Since two-piece toilets are more common, they are also more competitively priced.

There are also now highly sophisticated "intelligent" toilets that include features like adjustable- temperature heated seats or even self-cleaning functions that eliminate the need for toilet paper. 

Design: Toilets come in various configurations for different uses and needs. Among the considerations you can choose from: 

  • Bowl shape. When choosing a toilet, you can choose from those with bowls that are elongated, compact -elongated, or round-front. Elongated toilets offer deeper seating areas and will fit most residential applications. Compact-elongated toilets have a slightly shorter footprint and take up less space while still offering good comfort. Round-front toilets take up the least space and are a good choice where space is at a premium. 
  • Seat height. Standard-height toilets have a seat that is roughly 17 inches above the floor. Chair-height toilets are slightly taller at about 19 inches above the floor, making them much easier to use for older people or those with mobility limitations. There are also custom-height toilets that mount on the wall and can be set at heights ranging from about 15 inches to 28 inches above the floor. 
  • Toilet trap. Toilets can have trap configurations that are exposed—where the integral trap in the fixture is visible from the side—while in others, the trap configuration is hidden by the design of the fixture, so that the side view of the toilet offers a flat surface. This is really a matter of aesthetics: visible-trap toilets are a good choice for classic-style bathrooms with pedestal sinks and free-standing tubs, while hidden-trap toilets may look better in more modern bathrooms. 
  • Flush-handle locations. Toilet handles that operate the flush mechanism can be either on the left or right side of the tank, or may be placed on the top lid. There are also touchless flush models, in which a simple touch anywhere on the tank initiates the flush. And today, there are even toilets with electronic remote-control flushing systems. 

Flushing technology: Most toilets you buy today will be water-saving models when compared to older toilets, but there are several options to choose from.

  • Single flush. These toilets deliver the same consistent flush with every use. Most use about 1 to 1.5 gallons per flush, though models that use even less are available. Because it is the most common, this type offers the widest range of designs, shapes, and colors. 
  • Dual flush. These have a two-stage lever mechanism that offers either a light flush for liquid waste or a full flush for solid waste. LIght flushes use as little as .6 gallons of water, while the heavy flush uses around 1.5 or more gallons. 
  • Touchless flush. These toilets have a battery-powered electronic sensor that initiates the flush just by a wave of the hand over the sensor eye. Because there is no physical contact, there is little chance of spreading germs.

Buying a New Toilet

New toilets can vary widely in price, ranging from less than $100 for basic economy models to upwards of $5,000 or more for intelligent toilets using electronic technology. Once you have selected a replacement toilet, make sure that you also purchase any components that are not included, such as a wax gasket and closet bolts. Many toilets today come with the water-supply (ballcock) valve already installed in the tank to make installation easy, but it's possible you may need to buy this part separately, too. Whenever replacing a toilet, it's also a good idea to replace the water supply tube and shutoff valve. 

Use caution when transporting and installing your toilet. Nearly all are made from vitreous china or porcelain, and they will crack or shatter if dropped.

More than one DIYer has shattered a toilet when it was accidentally dropped during installation.