10-Inch to 12-Inch Toilet Adapter: All You Need to Know

The first step to replacing a toilet is measuring the size of the one you have now. Moving from a 10-inch to a 12-inch toilet doesn’t have to be expensive. You only need to confirm the rough-in size is 10-inches and buy a 10 inch to 12 inch toilet adapter.

What Is a Rough-in Size?

The rough-in size is the gap from the wall to the center of the drain pipe on the floor. This drain pipe on the floor is sometimes called a sweep or a flange. For accuracy, make sure to measure from the center.

The rough-in size will dictate if you have an easy installation or if you’ll need adapters. In a perfect world of plumbing, a toilet’s “rough-in” size will be the same as the hole you’re placing it in. 

Toilet rough-in sizes vary between brands. A standard size is between 10-inches and 14-inches. But, older homes usually have 10-inch toilets. 

That said, don’t guess what size your toilet is. Measuring is the most important part of replacing your porcelain throne, and it only requires a tape measure.  

How Do You Measure Rough-In?

I’ve found the best method for measuring the size of your toilet rough-in is to press the end of a measuring tape to the wall and pull the tape measure to the bolts on one side of the toilet. 

The bolts are a handy guide for measuring. They align with the center of the drain flange and keep you from having to remove the old toilet to measure. Don’t worry about the decorative caps covering them. 

The key to getting an accurate measure is to measure from the wall to the center of the bolt. This is the rough-in size.  

Like people, toilets can have one side of the body longer than the other. Measure both sides and compare. 

What About the Size of the Drywall?

When you measure, you may not get a perfect round number. You may measure 9.5 or 9.75 inches on a 10-inch toilet or 11 3/8 on a 12-inch. This is because the wall has had drywall added. 

The rough-in measurement doesn’t account for the hidden drywall mounted to the wall. This means that the number will vary based on the thickness of the drywall. 

Most older homes with a 10-inch rough-in will have used quarter-inch drywall. This means you’ll likely get a measurement of about 9 and ¾ inches. 

Unless your walls are bare, you will have a few other measuring considerations. Consider if you have wiring from heating floors or thick wainscotting. Extra large bases can also be an obstacle to getting a proper measurement.

Once you have a measurement of 10, 12, or 14-inches, you know the size of the toilet you currently have installed. Now you can start looking at a replacement. 

If you’re indecisive, I’m here to tell you that you don’t have to stick to the number you measured, thanks to adapters. 

You can install a 12-inch toilet into a 10-inch rough-in. You will need an adapter for a proper fit. Buying a 12-inch toilet has its advantages. 

Since 12-inch is more modern, new and upgraded older homes no longer use 10-inch toilets. They will be replacing them with larger models. In response, companies have slowed the production of smaller styles.  

Should You Install a 12-Inch Rough-In Instead of a 10?

The short answer is: yes if you have the room. The list of options you will have with a 12-inch toilet is lengthy. 

Here are some criteria to consider if you’re still unsure.

More Features

12-inch is the modern size toilet for current, popular brands. This includes many pretty, comfortable toilets with extra features. You could buy a toilet that self-cleans, has a bidet, heated seats, and more. 

Beyond looks and add-on features, there’s practicality. 

A 12-inch rough-in toilet is large enough to allow for the installation of a dual flush. This two-button flush system can move larger volumes of water with one button. Or, there’s also the option for an eco-friendly flush that uses less water. 

Bowls and Tanks

Besides the rough-in size differences, there is also a difference between the bowl and tanks. 

Newer 12-inch models also tend to skew towards comfort heights. These comfort toilets have taller bowls. This makes it easier for tall people and seniors to sit comfortably. 

There are so many options that, when in doubt, check the specifications of the new toilet. Look for the rough-in measure before paying for fancy features that won’t fit in your home. 

These sizes affect the manufacturers’ style available. There’s no industry standard from company to company.

Consider Bathroom Size

When installing a 10-inch to 12-inch toilet adapter, consider the bathroom size because it could make it very difficult to maneuver in a smaller bathroom that suddenly has a larger toilet. The larger fixture could also look out of place if you have a small bathroom. 

Spend some time looking at specifications and features. 

Determine what will look best in your space before removing or installing the new toilet. Hauling them back and forth from the hardware store will become a huge chore.  

10-Inch to 12-Inch Toilet Adapter

Now that you have:

  • Completed all the necessary measuring 
  • Opted to install a 12-inch toilet into a 10-inch rough-in
  • Chosen the toilet you want to buy 

You will want to purchase the toilet and a 10-inch to 12-inch adapter

How It Works

On most toilet bowls, you can see the distinct form of a channel behind the bowl. That channel is usually around 2 inches in diameter and can form an S or a U shape. Regardless of the shape, this channel is the wastewater pathway to the drain.

When installing a 10-inch to 12-inch, some manufacturers are using what’s called an offset adapter. The adapter works by stopping that S or U-shaped channel at its narrow point before it widens out to the drain size, creating a new path. 

Since the adapter forces the channel into a new path, it frees up space and allows us to shift the toilet forward or back 2-inches. This lets the toilet line up with the drain, so you don’t have to cut out pieces of your wall. 

Skirted Toilets

Most toilets have a side channel that widens from about 2 or 3 inches. It can get as broad as 3 or 4 inches. This is what a plumber will call a skirted toilet

Vitreous China, or coated porcelain, forms a skirt that starts about 4 inches away from the base of the drain. While it depends on the toilet, you often can’t see where it starts.

The company Toto has a product line of adapters that they’ve been producing for years. The offset adapter Toto uses, which fits a skirted toilet, is a “UniFit” or Universal Fit Offset Adapter. This adapter fits inside the toilet’s base and creates a new pathway inside the skirt. The top of the adapter will pressure fit to the top of the skirt.

The offset adapter lets you ignore the form of the toilet’s skirt as it determines how it fits. 

Remember, while universal is in the name, the adapters are not genuinely one-size-fits-all. You will have to order an adapter that fits your particular drain flange.

Wrap Up

You are now ready to take some measurements and make an informed purchasing decision.  A 12-inch toilet is usually the best option, and you will have many beautiful and functional toilets to choose from, provided it will fit comfortably in the room with space to walk around it. Just don’t forget your adapter in the process.

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