toilet rough-in

What Is The Toilet Rough In Size?

A toilet rough-in is one of the most important components of installing a new toilet. This is the distance from your bathroom wall to the middle of the floor drain in your toilet.

If you set your toilet too close or too far from the wall, you’re going to have major problems with the rest of your installation.

Here’s a basic breakdown of how to handle the rough-in measurements.

How Do I Know The Rough-in Size Of My Toilet?

rough in size

The majority of toilets are built with a rough-in size of 12 inches. With that said, you might find 10 inches with some models or bathrooms.

There are even rare occasions in which you’ll find a rough-in of 14 inches.

Always make sure that you take the measurements beforehand. When you go shopping for a toilet, you want to buy one that’s compatible with your bathroom.

These are the components that you need to measure if you want to know the rough-in size:

  • The distance from the back wall that you will set the flange
  • The left-to-right clearance
  • A comfortable amount of space in the front of the bowl
  • The placement of the cold water line

If you put the toilet too close to the wall, you won’t be able to set the flange properly. You also want to make sure that every other part of the plumbing can be easily hooked up to the model.

How Far Should The Toilet Be Off The Wall


The biggest component of the rough-in size is how far the toilet should be off the wall. For the most part, your goal will be to put the center of your flange at 12 inches away from the wall.

Even if you get a toilet with a rough-in size of 10 inches, it can still be maneuvered in a 12 inch space.

One important note is that you should not measure the toilet placement from the molding on the base of the wall. Measure it from the actual finished wall.

Depending on how thick your molding is, this can make a big difference.

On the other hand, if you are using stud walls instead of finished walls, then the thickness of the wall should factor in. Drywall tends to be 0.5 inches, so if you’re measuring from an unfinished wall, you should try to get 12.5 inches instead of the standard 12.

You can find the rough-in size for any toilet model on the specification sheet. While most models have a 12-inch size, some come in 10 or 14 inches.

How Much Clearance From The Toilet Center For Fixtures Or Walls?

The center of the toilet needs to have a certain amount of clearance before you reach the bathtub, sink, another wall, or any other fixture. This gives you room to install the model and its plumbing properly.

You need to have at least 15 inches between the flange and any obstruction to the left or the right.

If you’re looking at a stud wall, you’ll also need to add the wall thickness. So you’ll want 15.5 inches of clearance between the toilet flange and an uncovered, unfinished wall.

Make sure you also take into account the thickness of any tiling you’re thinking about adding to the wall.

How Far From The Front Of The Toilet To The Wall?

There needs to be a certain amount of space in front of the toilet. You want to have room to sit down comfortably, after all!

The regulations for this will vary depending on the local codes. For local codes that adhere to the International Plumbing Code, the requirement is 21 inches at the very least.

For local codes that adhere to the Uniform Plumbing Code, that distance increases to 24 inches.

Plumbers in your area should be aware of the local codes of your city or town. You can consult one if you’re having trouble finding information about the specifics.

The amount of space is between the toilet and any obstruction, including the door, walls, or other appliances. With that said, you don’t need this much space in front of an open bathroom door.

It’s only for when the door is closed.

Where Does The Supply Line For Cold Water Go?

You will need to attach your toilet to the supply line for cold water. That’s where it will get the replenished tank after each flush.

Fortunately, measuring for this line is fairly easy. First, locate the center of the flange. Then measure just six inches to the left.

Once you’ve found this spot, measure seven inches vertically above the floor tiles. That’s low enough to stay out of the way, but it’s also high enough to avoid damaging most types of base molding.

If you measure too low, you’ll have to notch the trim.

It’s common for plumbers to put the supply line six inches above the floor. While there’s nothing technically wrong with that, it might cause you to need to change any trim that’s higher than 5 inches.

What Is The Difference Between A 12 And 14 Rough In Toilet?

The main difference between these toilets is the size of the rough in. A 12 inch model is more common than a 14 inch one, because this tends to be a more standard size.

A 14 inch rough-in is sometimes used when people need to have less space taken up behind their toilet tank.

How To Know If Your Toilet Is 10 Inches Or 12 Inches

how to know the size

When you’re shopping for a new toilet, the specs page should tell you whether the rough-in is 10 or 12 inches.

If you want to know about your current model, you will simply need to measure the distance from the middle of the flange to the back wall. Is it 10 inches or 12 inches?

Make sure you don’t factor in the base molding on the wall.

You can fit a 10 inch toilet into a 12 inch rough-in. But it will have a little extra space behind it.

If you find that your flange is only 10 inches from the wall, you should only look for 10 inch rough-in options.


The rough-in size for your toilet will depend on your plumbing and the toilet model. While most have a size of 12 inches, you’ll also sometimes find 10 and 14 inch models.

You can fit a 10 and 12 inch rough-in model into a 12-inch flange setup. Measurements are taken from the middle of the flange to the back wall.

If you’re unsure how to determine the local building regulations for your toilet installation, you can talk to a local plumber about the requirements.