10 Vs 12 Inch Rough In Toilet – A Detailed Comparison

Written by

Paulk Webb


Freddie J. Hagopian

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10 vs 12 inch rough in toilet

Before discussing the size, what does rough in mean for toilets? It’s mostly found behind the toilet where the water outlet is situated. The measurement of the rough in is the gap from the outlet’s center to the toilet’s back that faces the wall. Every buyer should know this as it’s an important factor when purchasing a toilet.

Thus, 10 vs 12 inch rough in toilet is a comparison that you have to pay attention to before making a purchasing decision. 12-inch rough-in is the standard size for one-piece and two-piece toilet styles. You can still find 10-inch rough in toilet, but it’s not common. To decide which one suits your needs, read about the difference between 10 inch and 12 inch rough in toilets in this article.

Details of 10-Inch Rough in Toilet

What is a 10″ rough in the toilet? It’s the 10 inches space from the wall to the opening center of the floor flange. There are only a few toilets with 10-inch rough in. They are usually seen in old houses and buildings. During toilet renovation, make sure you buy a toilet that fits the available 10-inch rough in.

This rough in size is perfect for powder rooms and small bathrooms. The best examples are the American Standard Cadet Pro (two-piece), Kohler Cimarron K-3851-0, and Toto Drake Washlet.

1. Advantages

  • Space saver
  • Perfect for small bathrooms
  • Accommodates kids and pets
  • Can be converted to 12-inch rough in

2. Disadvantages

  • Limited options
  • Costly
  • More prone to clogging
  • An increase in dampness, sweating, and humidity because the water closet is connected to the wall

Details of 12 Inch Rough in Toilet


What is a 12 inch rough in toilet? It’s 12 inches opening from the wall to the opening center of the floor flange. This is the standard rough in measurement these days, and there are variations to choose from. However, my top picks are Kohler Persuade K-3654-47, Sterling Windham 403080-0, and Toto Drake CST744SL.

1. Advantages

  • Not likely to clog
  • Has stronger flushing power
  • Can be used by everyone
  • Suitable for small and large laboratories
  • Several toilet options
  • No sweat or dump tank

2. Disadvantages

  • Cannot convert 10 inch rough in

For Comparison: 10 Inch vs 12 Inch Rough in Toilet

Before making a purchase, it’s normal to think over 10 or 12 inch rough in toilet so you won’t regret your decision. Here are the essential factors:

  • Measurement

The 10 inch rough in is usually found in old houses while the 12 inch rough in is recognized as the standard size nowadays. The 10 inch rough in a toilet has fewer options. On the other hand, 12 inch rough in toilets have a lot of options. They are in one-piece, two-piece, elongated or round, and standard or chair height. Some of them have water-efficient performance.

  • Clogging issue

The 10 inch rough in toilet is prone to clogging, whereas, the 12 inch rough toilet won’t bother you with it.

  • For those who live in humid regions

It’s best to have a 12 inch rough in the toilet when you live in a humid region. Since the 10 inch rough in the toilet is prone to dampness and mold growth, it can cause disaster.

  • Water consumption

In the past, 1.6 GPF or gallon per flush is what people expected from a 10 inch rough in toilet. At present, the water consumption is lowered to 1.28 GPF, which is one of the functions of a 12 inch rough in toilet. This GPF is even imposed by CALGreen and the California Energy Commission as a regulation.

You can save a lot from your water bills if you have a toilet that works with 1.28 GPF. But you shouldn’t forget that there must be an incredible flushing performance to clear the toilet with waste without the need to make another flush.

How to Determine the Size of the Rough in Toilet


At this point, you know what is rough in size for a toilet. But you may not have an idea about the exact measurement of the one that you have in your bathroom. This is crucial when replacing a toilet, and you can do it through a tape measure or ruler. You may need a pencil or marker as well.

1. Floor-mounted toilets

  • The very first thing that you have to measure is the drain opener. In this step, you have to find the center and mark it.
  • Measure from the wall to the caps of the bolt. These bolt caps are found at the toilet’s base, and they tighten and seal the whole toilet system.
  • If there are more than two caps, you have to include rare bolts in measuring the rough in.
  • If there’s a stud wall, you need to include the solid wall in the measurement.

2. Corner-mounted toilets

  • Begin with stretching the measuring tape at both angles up to the bolt caps. Take note of the position of these parts so you can have precise measurements.
  • At both points, you have to draw perpendiculars.
  • You’ll find the rough in at the points that overlap with each other.

How Do You Replace 10 Inch Rough in With 12 Inch Rough in?

Although 10 inch rough is old school, one of its strengths is the possibility to convert it into 12 inch rough in. It’s done by adding an offset flange that connects the toilet flush outlet to the primary drainpipe. A toilet flange is an adaptor that allows the transfer of rough in and prevents damage at the same time. It’s also open to the change of direction.

During its installation, it should be ¼” above the floor to give some space when pressing the wax ring. See to it that you create a tight toilet seal.

Guide on Offset Flange Installation

  • Measure the drain opener that can be 3 or 4 inches wide.
  • Get an offset flange that matches the size of the rough in. The appropriate wax ring and bolts are also essential to create a tight seal.
  • Cut off all the water supply lines that are connected to the toilet.
  • Flush the water from the tank and take out every bit of water using a sponge before removing the tank lid.
  • Before detaching the old toilet, prepare an old towel or cloth. You have to carefully put the toilet on the towel or cloth.
  • Take out the old wax ring and clear out the sections around the base.
  • Put the new flange in.
  • Add the wax ring and bolts to attach the toilet securely.
  • Link the waterline to initiate the operation.
  • Flush to check if there’s leakage once the tank fills up.

Closing Words for Rough in

If you have limited space in your bathroom, it’s best to get the 10 inch rough in toilet. When it doesn’t work as expected, you can replace it with the 12 inch rough in. There are various options of 12 inch rough in toilets that you can’t find from ones with 10 inch rough in. Hopefully, this article about 10 vs 12 inch rough in toilet has been helpful.

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