Is There A Standard Size For Toilet Seats?

Used day in day out, year in year out, toilets do us a noble service. In fact, it is estimated that a family toilet seat will be raised and lowered around 1,500 times in a single year.

Is There a Standard Size for Toilet Seats?

This makes home toilet maintenance a given, as nothing so readily used and abused can last forever. 

When your toilet seat does come to its untimely demise (hopefully not while someone is on it), you will need to secure a new one.

In enters the question, is there one standard and universal size for all toilet seats? In short, no there is not.

To the untrained eye, toilets may look the same, but once you know what to look for, you realize they are all rather unique.

This article is here to dispel the myths and deliver the facts on toilet seats and their sizes, once and for all. 

Is There A Standard Size For Toilet Seats?

As we previously hinted, there is no such thing as a “one seat to fit all toilets” approach to sizing up toilet seats.

In saying that, here in the U.S there are two standard toilet shapes that subsequently equate to two standard toilet seat sizes.

These standard toilet shapes are known in the industry as elongated and round.

To figure out which type of toilet you have we will highlight exactly what an elongated and round toilet represents so that no mistakes are made. 

What Is An Elongated Toilet Seat?

An elongated toilet seat is exactly that, it’s elongated. Elongated toilet seats are not thinner in width, they are longer in length.

This extra length makes them a great option for particularly tall and large people who require a bigger toilet seat.

As a result of elongated toilet seats suiting tall people as well as shorter people, they are the most common toilet seat type for public toilets and businesses.

Most hotel, airport, and shopping mall toilets will be elongated for this reason. 

However, just because they are the preferred choice for public and business toilets, they are a popular choice for the home as well.

If you have a husband and growing boys, fitting your home with an elongated toilet is a clever idea as it will minimize the chances of them missing the toilet bowl. Size-wise, elongated toilet seats, in general, measure up to 18.5 inches long and 14 inches wide.

What Is A Round Toilet Seat?

Round toilet seats are most commonly fitted in the home environment.

This is because, as a general rule of thumb, most homeowners tend to prefer extra bathroom space instead of a larger toilet.

Unlike their more elongated counterpart, round toilets are stubby in shape, with their length being not a whole great dealer longer than their width.

You will find that the majority of round toilet seats come in at 16.5 inches in length and 14 inches in width.

This reduced length means they can fit into tighter toilet-specific spaces and rooms which is another reason why they suit the home environment best.

It is rare to find a round toilet in a public set of toilets, but it does happen.

Also, another thing to consider is their reduced size means they are often a little bit cheaper than the elongated toilet seat variety.

Unless you are fitting a new toilet in your home, your decision as to which toilet seat to look for has already been answered.

Why? Because it is not recommended to fit an elongated toilet seat to a round toilet and vice versa.

The toilet that you have dictates the toilet seats you can shop for. The key here is to know, for sure, which toilet seat you need.

What If Your Toilet Isn’t Elongated Or Round?

Like we said, most U.S toilers are either elongated or round in shape.

Installing either one of these toilet types means you will have plenty of choices when it comes to choosing a new toilet seat.

However, having an elongated or round toilet at home isn’t always the case.

Some toilets and their toilet seats dare to be different, with bespoke designs and shapes that buck the elongated and round trend. 

There is no rhyme or reason as to which home is likely to be fitted with such a toilet.

It could be a futuristic toilet fitted in a stylish and contemporary home just as easily as it could be an antique toilet fitted in a stately mansion of the past.

They may feature a pan that is closely connected to the cistern to give it a more refined style, or they may be a completely different style altogether.

We’re talking back-to-wall toilets, wall-hung toilets, and high-level toilets, the list of rare toilet types can go on and on.

This is especially the case when you factor in all the toilet styles that different cultures from around the world use on a daily basis. 

The more peculiar toilet types will generally not match the exact width and length of the industry-standard elongated and round toilets.

They can measure as small as 13 inches right the way up to 20 inches and beyond for the more grandiose styles.

This discrepancy means measuring your toilet before you look to replace a toilet seat is essential.

How To Measure Your Toilet Seat?

Learning how to measure your toilet in order to buy a toilet seat is a critical first step in finding the right seat from the offset.

Is There a Standard Size for Toilet Seats?

There is no such thing as winging it when it comes to toilet seats.

You need to know exactly how big (or small) your toilet is before you start to peruse the toilet seats of your local hardware store. 

So, now that you have a good idea of whether your toilet seat is elongated or round, it is time to find your tape measure and size it up.

The three key measurements for figuring out the overall size of a toilet seat are its length, width, and seat post holes.

Once you have these three measurements, you will officially be ready to drive down to the hardware store and select your new and improved toilet seat. If you are shopping online, the same rules can be applied. 


Length is a toilet seat’s most important measurement. Why? Because it is the measurement that is most likely to differ.

As we already know, the width on standard elongated and round toilet seats rarely differs from 14 inches, whereas the length does. 

To measure a toilet seat’s length you must first lift up the existing toilet seat (if there is one).

Place your tape measure directly in the middle of the seat post holes and stretch it out until it reaches the end of the bowl – this is your toilet seat length.

A tip for this is to remember that your toilet seat sits flush with the end of your toilet bowl.

For this reason, you must take the measurement at the outside edge of your toilet bowl.

If you take the measurement on the inside edge of the toilet bowl, or even the middle of the rim, this will be an incorrect measurement. You may, subsequently (and annoyingly), buy the wrong toilet seat because of it. 

From your toilet measures 18.5 inches from the middle of its seat post holes to the outside edge of its bowl, you will need an elongated toilet seat.

If, however, it measures 16.5 inches, your toilet is officially a round one and you will require a round seat accordingly. 


As you already know, the width of a toilet seat is mostly of standard size in the U.S, but this isn’t always the case.

If you only take one measurement of your toilet the length is definitely the one to take.

But, seeing as you already have the tape measure out and the toilet seat up, you might as well double-check the width, right?

The width of a toilet seat is determined by measuring the width of the toilet bowl.

Again, just like the length, to correctly measure the width you must measure from the toilet bowl’s outside edge on one side to the other outside edge.

If this measurement is 14 inches, you have nothing to worry about. If, however, this measurement is larger or smaller than 14 inches you do in fact have a problem. 

The difference could be a half inch or several inches, the problem remains the same – you have a non-toilet seat on your hands.

This is perfectly fine, it just means you will have to do a little more shopping around to find the perfect fit. 

Seat Post Holes

Last and probably least, it is time to measure your toilet’s seat post holes. Why is it the least important measurement you ask?

Because it is the least likely to differ from the standard. What is considered a standard seat post hole measurement you ask?

Good question! The standard seat post hole measurement in the U.S is 5.5 inches.

If your seat post holes are 5.5 inches apart from each other this is a very good thing.

Standard seat post holes are great because they allow you to fit any standard toilet seat that you might have your eye on.

Elongated, it doesn’t matter. Round, that doesn’t matter either.

As long as your seat post holes square up to be 5.5 inches apart, you are sitting (on your toilet seat) pretty.

To find out whether your seat post holes stack up to the industry standard of 5.5 inches you will need to take a measurement between the two.

This measurement needs to be from the center of one seat post hole to the center of the other seat post hole.

Getting the measurement from center to center is critical as this is where the fitting will be.

How Do You Replace A Toilet Seat?

Replacing your toilet seat yourself really isn’t very hard if you have done your homework and have the right tools.

Once you have measured your toilet seat and bought a new one, it really shouldn’t take you a very long time to replace your existing toilet seat with your new one. 

To remove your existing seat you must unscrew the bolts of the seat posts. You will need a wrench to do this comfortably.

Without a wrench, even the strongest man on earth will struggle to remove rusty seat post bolts.

Once you have removed your existing toilet seat, it should be an easy task to fit your new one.

With the guidance of the instruction manual by your side, you will need to screw the seat post bolts back onto the seat posts with your new toilet seat in place of the old one.

If your seat post bolts are worn and rusty, we would suggest replacing them while you are at it.

You can buy such toilet fittings from any reputable hardware store that stocks toilets.


As you can see, there is no such thing as a toilet seat that fits every toilet.

With a little know-how and prior knowledge, however, it is an easy task to figure out which toilet seat your toilet is rocking.

We hope this article has helped you find the right toilet seat to offer you and your toilet many fine years of service.

Adrienne Carrie Hubbard