Are Toilet Seats Universal? No, But Standards Exist

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are toilet seats universal

Are toilet seats universal? No, toilet seats do not universally fit on every toilet. The reason is that there are several shapes available for you to choose from, each of which follow their own standards. Each toilet seat shape is universal due to these standards. Let's learn more so you can replace yours with confidence.

Installing a new toilet seat is one of the bathroom's quickest and easiest home improvement tasks. Many people pick up the first toilet seat they see at the hardware store only to find that it doesn't fit the bowl at home.

Find out if toilet seats are universal, so you don't have to go back and forth to the store and waste time. Read on to learn whether or not toilet seats come in standard sizes and which seat will work best for you.

Are Toilet Seats Universal? Are All Toilet Seats the Same Size?

are toilet seats universal? are all toilet seats the same size?

Toilet seats are not universal in design, but there are some standard measurements that almost all of them share, no matter if we're talking about plastic or wood toilet seats, elongated or round seats, etc.

Regardless of the design of your toilet bowl, the distance that separates the two bolts that secure the seat to the bowl is universal. There should be a distance of about 5.5 inches between the centers of these seat post holes.

Second, the breadth of the bowl of a toilet is typically the same, no matter the form. A half-inch or less in width variation is typical.

Next, let's review the most common toilet sizes and some guidance on determining the precise dimensions of your toilet seat.

Standard Toilet Seat Dimensions

In the USA, there are two common sizes for toilet seats across all the types of toilet seats you'll find out there. These sizes have two names: round and elongated. The standard size difference between elongated and round toilet seats is 3.5 inches (18.5 centimeters).

Those extra inches make a big difference in comfort for a larger or smaller person. Bigger isn't always better as it depends on the size of the individual person. Depending on your size, you can choose from your preferred standard toilet seat size, of which there are two to choose.

Round Toilet Seat Dimensions

round toilet seat dimensions

Around the world, spherical toilet seats have become the standard in homes and apartments. Because they are smaller, they are more commonly seen in powder rooms with limited floor space.

The typical dimensions for a round toilet seat are 16.5 inches in length and 14.5 inches in width.

Circular toilet seats are typically less expensive than elongated ones, if only because they are smaller by a couple inches.

Elongated Toilet Seat Dimensions

elongated toilet seat dimensions

The standard dimensions for an elongated toilet seat size are 18.5 inches in length and 14.5 inches in width.

Due to their increased dimensions, many people favor elongated toilet seats. Because this seat is used so often, it has become the standard in many public places and businesses. While you can find them in homes and apartments, they're most popular in commercial buildings.

Non-Standard Toilet Seats

As mentioned in this article, anything other than one of the conventional toilet sizes (18.5 or 16.5 inches in length) is considered a non-standard toilet and will need a non-standard toilet seat.

It's possible that they don't conform to the conventional size and shape or that the distance between their seat post holes isn't 5.5 inches.

Non-standard toilet seats may be an original equipment manufacturer seat or a European model. It's wise to avoid purchasing these types of toilets unless you want to have a headache every time you need replacement parts.

Original Equipment Manufacturer (OEM) Toilet Seats

original equipment manufacturer (oem) toilet seats are one of the non-standard toilet seat size

Manufacturers frequently experiment with novel forms and aesthetics to maintain their positions as industry leaders. They are offered in limited quantities to test the waters and determine if the market would bear these novel toilet designs.

There are two names for these sorts of toilets. Depending on who made them, these seats may be considered “OEM” or “proprietary”. Replacements for these seats can be challenging and costly in any scenario.

However, not all hope is lost because many plumbing supplies and do-it-yourself (DIY) businesses sell non-standard toilet seats for less than what they would cost to order directly from the manufacturer.

European Toilet Seat

european toilet seat sizes differ from standard sizes

If your toilet seat differs from standard sizes, it could be a European model. In addition to the more conventional elongated and spherical designs, European toilets frequently have seats with a D-shape.

The D-shaped toilet seat is readily available for online purchase and shipping. It's essential to have an accurate measurement before making a purchase.

Measuring Your Toilet Seat

measuring toilet and toilet seat dimensions

Are toilet seats universal? No, but there are standards, and now that you know the industry standards, you may wonder how to measure your toilet seat.

Before you head out to the hardware shop, you'll need these three measurements:

  • Seat length
  • Seat width
  • Post spacing

Get as accurate as you can but don't stress it. You're going to find there's very little variance once you reach the store. Unless you know it for sure, you're very likely using a standard toilet seat. You just need to determine which shape you have (round, elongated, etc.).

Seat Length

By far, this measurement is the most crucial. In most cases, the width and post spacing will be standard, so if you don't want to keep track of three separate numbers, this is your best bet. But to be sure you have a regular-sized seat, you should also measure the other two.

How To Measure Toilet Seat Length

The length determines whether your bowl is round or elongated. Begin your measurement from the back of the toilet bowl between the two holes in your seat post. Continue the measurement to the far end of your bowl. To get an accurate reading, measure the outside edge of the toilet bowl.

Seat Width

The width is often standard, but you should still measure it to ensure you don't have a standard-sized toilet. Simple measurements across the broadest portion of your bowl will give you this information. As before, make sure you measure from the outer edges.

How to Measure Toilet Seat Width

Place your tape measure on either side of the toilet seat at the broadest part of the outer curvature and measure directly across to the broadest part of the other side. Your toilet seat may not be the conventional 14 inches in diameter, so read on to learn what to do if you discover this is not the case.

Post Holes

You need to measure the diameter of the holes in the toilet seat post to ensure your toilet fits into standard studs. The distance between the two seat-post holes is the value you're looking for.

No regular toilet seat will fit if your toilet's post hole diameter is less than or greater than the standard 5.5 inches.


You might be able to find hinges for a new toilet seat that will fit a variety of seat post hole diameters. There's a possibility that this is less expensive than purchasing a unique toilet seat.

Of course, only some problems can be solved by replacing the hinges. For some situations, a custom-made toilet seat is required. Your toilet seat will be of a specific type based on the brand that made your bowl.

To verify you are performing the installation correctly, go to the manufacturer's instructions or website.

How to Get the Right Toilet Seat

getting the right toilet seat might be challenging for you if you are not feeling comfortable with standard toilet seat dimensions

You'll need to hunt down the company that made the original fixture to get a new seat for a toilet that doesn't use a conventional size.

The space between a toilet seat's post holes is sometimes used to display the brand's emblem or name. Remove your toilet's tank cover and look for a label from the manufacturer if it doesn't have one. If your toilet is OEM or proprietary, this is likely to happen.

You may find the manufacturer's logo right there between the seat posts. Check online for retailers that carry your seat size, or head to the hardware store and ask if they can order it for you.

Locating the manufacturer's label inside the toilet tank lid should lead you to the site where you may get new components.

Obtain the brand name of your specialty toilet from the manufacturer's website if you choose a more affordable alternative. It would help if you started looking for an alternate solution at plumbing supply shops. You should get several results if you type it into a search engine.

How to Replace a Toilet Seat

we have covered up whether are toilet seats universal or not, here is how to replace a toilet seat

Once you have your new toilet seat, replacement is easy with the following steps. Detach the seat posts to get rid of the old toilet seat. If the bolts are corroded, you might need a tool to loosen them.

It would be best if you also removed the bolts and nuts to remove any remaining parts of the old seat. This includes the toilet bolt caps and plastic nuts used to hold the seat down the toilet bowl. Remove all of these items before you install your new seat.

To install the new seat, put it in place and line up the hinges with the post holes. Secure the seat with the nuts and bolts provided. Make sure the bolts are snug but not overtightened.

While you’re already down there, now is a good time to optimize the energy usage of your toilet. You can reduce the amount of water you’re using significantly, which will equate into savings for you and less stress for the municipality in general.

So, Are Toilet Seats Universal?

Hopefully, this article has helped you understand the basics of toilet seat sizes. The key takeaway is that many different types and sizes of toilets and toilet seats are available for purchase.

Whether you're looking for a standard or elongated toilet seat, it's essential to know what size will fit your needs before making a purchase decision. So, are toilet seats universal? No, but they are if you stick to the same size standard.

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