Are Toilet Seats Universal? (Size Guide)

Whether your old toilet seat has worn out or you’re ready for an upgrade, you’ll probably shop for a new one at some point. There are lots of options, and it can get a little bit confusing. With so many choices available, you may wonder if toilet seats are universal.

Are Toilet Seats Universal

In this article, we’ll tell you the dimensions of the standard toilet seat and give you tips on measuring your current toilet seat. We’ll also tell you if toilet seats and hinges are interchangeable and what shapes toilet seats come in.

Are Toilet Seats Universal?

Unfortunately, toilet seats aren’t universal. There are round and elongated toilets and toilet seats, and one cannot be substituted for the other. Within the two categories, though, the seats are interchangeable if you have a standard-size toilet. You will have to take measurements to see if your toilet is standard-size.

Toilet Seat Styles

The two main styles of toilet seats are round and elongated. Some European countries also have D-shaped toilet seats. No matter what toilet seat style you have, when it’s time to replace it, you’ll need to measure your toilet to see what size seat will fit. 

When it comes to the dimensions of your toilet, there are a few measurements that are the same across the board. The distance between the bolts that hold the toilet seat in place should be about 5.5 inches, and the width of the bowl should be about 14 inches.

If your measurements differ, you have a non-standard toilet and must choose your replacement toilet seat carefully.

That said, let’s take a look at the standard length of the two main toilet seat styles, elongated and round. You also need to decide on whether you want a wooden or plastic one (there are pros and cons to each).

Elongated Toilet Seat Dimensions

In the United States, the standard dimensions of an elongated toilet seat are 18.5 inches long by 14 inches wide. You’ll usually find elongated toilet seats in public restrooms and in hotels. Occasionally, people will put elongated toilets in their houses or apartments, but it’s uncommon.

Round Toilet Seat Dimensions

The standard dimensions of a round toilet seat in the United States are 16.5 inches long by 14 inches wide. These toilets are commonly found in private dwellings, like houses and condos.

Since they are a little smaller than the elongated toilets, they fit better in smaller bathrooms and can be a bit more economical for homeowners.

How To Measure A Toilet Seat

Now that you know what the standard dimensions are for both types of toilet seats, the next thing you need to do to ensure the proper fit is to measure your toilet.

measuring a toilet seat

Let’s take a closer look at the steps involved in determining if you have a standard-size toilet.

1. Length

Since the length is the biggest variable on toilet seats, it will also be your most important measurement. To find it, just measure from the center of the bolts that hold your toilet seat to the outer edge of the toilet bowl.

2. Width

Most toilets are 14 inches wide, but you’ll have to measure yours to make sure that you have a standard-size toilet that is compatible with most toilet seats. All you need to do is find the widest point on your toilet bowl and measure from one outside edge to the other.

3. Post Holes

The post holes are where the bolts that hold the toilet seat in place connect with your toilet. The standard distance between these holes is about 5.5 inches. If that’s the width you get when you measure your toilet, any seat with the right length and width will fit.

What Are Non-Standard Toilet Seats?

If you take your toilet measurements and discover that you have a non-standard toilet, that’s okay. Finding a replacement seat will take a little more effort, but you still have options. 

If the only size difference is the distance between your post holes, you can buy replacement hinges to make most seats fit your toilet. However, if the length or width deviates from the standard, you’ll have to special order a replacement seat instead.

Are All Toilet Seats Interchangeable?

No, unfortunately, toilet seats aren’t always interchangeable. For instance, manufacturers sometimes release a new toilet style to see if the public likes it.

Finding a replacement seat for these special toilets can be challenging, but you can always order them directly from the manufacturer’s store.

Occasionally, you can even find after-market replacements for these toilets at your local hardware store that cost a little less than ordering from the manufacturer.

If you have a non-standard toilet, you’ll have to look for the manufacturer’s name. You can usually find this information between the post holes, but if you don’t see a name listed there, just look inside the tank.

Most manufacturers put a label in the tank, so you’ll be able to take the information from that label and look it up online to find a replacement. Once again, it will be cheaper if you can find your toilet seat at a hardware store, but sometimes your only option will be to buy one directly from the manufacturer. 

It’s not very common in the United States, but occasionally, you might find that your non-standard toilet is actually European. Remember, European toilets also come in D-shape.

These don’t have a standard size, so you’ll have to measure your toilet, then shop online to find the right size replacement.

Are Toilet Seat Hinges Universal?

Just like toilet seats, the hinges are also not universal. The most common type of hinge, the fixed hinge, must be measured correctly to fit your toilet and your toilet seat, or else you will have to modify your toilet seat.

Modifying your toilet seat takes more skills than your average DIYer will have, and they won’t ever look like they were made that way.

If you have a non-standard toilet where the only deviation is the post hole width, there are replacement hinges you can buy.

These hinges are called adjustable hinges and can change the position of the seat when you install them. These hinges can shift over time, so you should check and readjust them at least once per year.

How To Replace A Toilet Seat

Replacing a toilet seat is a quick, easy task that can improve the look of your bathroom and make your time sitting on the toilet a bit more comfortable.

replacing a toilet seat

Just follow these simple steps, and you’ll have your new seat on in no time.

1. Remove The Old Seat

Before you take your old toilet seat off, clean it thoroughly so you can reach the bolts that attach it to the toilet. Remove the bolt covers, then use a wrench to loosen the nuts that hold the bolts in place. Take out the bolts and remove the toilet seat and hinges from your toilet.

2. Unpackage The New Seat

Take your new toilet seat out of the packaging and check to see that all the necessary hardware is included. Position the seat over the rim of your toilet and line up the hinges with the post holes. Grab a level and make sure the seat is balanced correctly.

3. Attach The New Seat

Put the bolts through the hinges and feed them into the post holes. Make sure the head of the bolt is on top of the toilet seat. If your kit includes washers, slide them up the other side of the bolt one at a time and hold them in place until you attach the nuts.

With the washer in place, thread the nuts onto the other end of the bolt and tighten them with your wrench. It’s okay if your kit doesn’t have washers, just skip straight to the bolts instead.

When the seat is in place, attach any bolt covers or hinge covers included in the kit, and you’re finished.


How can I choose the right size toilet seat replacement?

To pick the right replacement toilet seat, you’ll need to get three measurements from your toilet. First, measure the distance between your post holes.

Next, measure from the center of your post holes to the outer edge of your toilet seat to get the length. Finally, find the widest point on your toilet bowl and measure from edge to edge to get the width.

Why do public toilet seats in America have a gap in the front?

Public toilet seats in the United States have a gap in the front to promote good hygiene. This design feature enables women to wipe front to back without touching the toilet seat. 


Toilet seats come in two common styles, elongated and round. While these seat types aren’t interchangeable, there is a standard size for both shapes. To determine what shape you have, just measure your toilet seat. 

If your toilet measurements deviate from the standard size, you have a non-standard toilet. Though you can still get replacement seats, you have fewer options available and may have to pay a high price for a seat that comes straight from the manufacturer.

If only your post holes measure differently than standard, you can buy replacement hinges that will help you modify a toilet seat to fit your toilet and keep costs down.

Shauna Stone