When you shop through links on our site, we may receive compensation. This educational content is not intended to be a substitute for professional advice or consultation.

What Size Toilet Seat? Tips for Measuring Toilet Seat Sizes

Knowing how to measure your toilet seat is crucial. We show you how.

Choosing a new toilet seat may not seem that important, but it could be the difference between a comfortable experience and a numb backside. Plus, you need to factor in other family members because it’s not always about you.

Here is our handy guide to toilet seat sizes, as we compare the shapes, sizes, and designs to see which one is the best for you and your family.

Key Takeaways

  • Round vs. Elongated: Round toilet seats measure 16.5 inches in length and 14 inches in width, while elongated seats measure 18.5 inches in length and 14 inches in width.
  • Measuring Length: Measure from between the seat post holes to the outer edge of the front of the seat to determine if it’s round or elongated.
  • Measuring Width: Measure the widest part of the bowl, which should equal 14 inches for standard toilet seats.
  • Seat Post Holes: The distance between the centers of the seat post holes should be 5.5 inches, which is an industry standard.

Are Toilet Seats Universal?

While toilet seats are not universal, the distance between the two bolt holes that fix your toilet seat to the bowl is pretty much standard across all makes and models. These are called seat post holes, and they generally measure 5.5 inches from the center of one hole to the other.

The most common toilet seat style is the elongated and round models, although round seats are losing ground to the elongated versions as they become increasingly popular.

Some toilets are European, especially those that cater to the D-shaped design, and they might not fit standard US size toilets.

Toilet Seat Sizes

As we’ve already said, the most popular toilet seats in the US are the round and elongated versions, but what are the differences between the two?


Round Toilet Seat

Round toilet seats are still in demand, with many families with small children preferring them to elongated versions. Round seats have less space for children to fall through, making them safer. They are also more comfortable to sit on for larger people.

In the main, round toilet seats measure 16.5 inches in length and 14 inches in width. The shorter length means they are better for smaller bathrooms because they take up less floor space. For this reason, they are often cheaper, but only slightly.


Elongated Toilet Seat

Elongated toilet seats are becoming more popular, especially with men who like to sit and pee. They are roughly 2 inches longer in length, which gives men the clearance they need to make peeing easier and more hygienic.

You get fewer splashes and drips, so the toilet seat is easier to keep clean. Most elongated toilets measure 18.5 inches in length and 14 inches in width. The extra 2 inches means the toilet takes up more floor space.

How To Measure Your Toilet Seat

Now you know the differences between round and elongated toilet seats, it’s time to get down to the nitty-gritty and learn how to measure your toilet to determine what type of seat you need.

Grab a tape measure, and let’s get started.


The length is the most important of all the measurements. The seat post holes and the width are fairly standardized, but the lengths vary according to the model and style.

Measure from in between the seat post holes to the outer edge of the front of the seat. You need to measure the outer edge to the outer edge to get the correct dimensions.

The length determines whether you have an elongated or round bowl.

To Recap

Elongated seats measure 18.5 inches, with round ones coming in at 16.5 inches. A good tip is to measure twice so that you only have to buy once.


Do the same with the tape measure, working from the outer edge across the width of the toilet. Measure the widest part of the bowl to get the maximum dimensions.

It should equal 14 inches, so if you have a different set of numbers, you might have a non-standard toilet.

Seat Post Holes

To get the correct measurement of the seat post holes, find the middle of the hole and measure to the center of the other hole. It should be 5.5 inches, which is an industry standard. You don’t need to remove the seat to do this, just find the center of the existing bolt.

What Is a Non-Standard Toilet Seat?

A non-standard toilet seat is basically any seat that does not meet the standard measurements set above. It could be because of the shape or the design, or maybe you have an antique toilet that was made before standard sizes were invented. You might also have a foreign toilet, where the size standards differ.

If the seat post holes don’t match, you can buy replacement hinges to cater to the different sizes; however, it might be cheaper to get a seat that fits.


How Do You Know What Size Toilet Seat You Need?

If you have a non-standard toilet, you need to find the manufacturer and approach them for the correct size seat.

Most toilets have a logo between the seat posts. It might only state the model, but some have the full name. If you can’t see any logo, lift the toilet tank lid and check underneath. It should be printed there.

You should be able to search the manufacturer’s website to source the replacement seat. It could also be a European toilet seat, which might explain why it is non-standard in size. While the designs may be similar to US seats, European styles also include D-shaped seats.

Sourcing a replacement D-shaped seat is pretty easy because you can order it online and get it shipped overseas to the US.

Is There a Toilet Seat Size Between Round and Elongated?

There isn’t a size between elongated and round, but there are many different styles of toilet seats to choose from. You can get D-shaped seats that are mostly European. These fit concealed tank toilets and wall-hung models because they are sleek and very modern in design.

You can also get open or U-shaped seats that have the front section cut away. These are great for hygiene because you don’t get splashes and drips trapped under the seat rim. For this reason, you are more likely to see U-shaped seats in public toilets.

Are Toilet Seat Hinges Universal?

On the whole, toilet seat hinges are universal in that they fit the seat post holes measuring 5.5 inches from the center of one hole to the other. Some non-standard toilets do exist, but you can buy specialist hinges to fit.

Do Toilet Seats Have a Weight Limit?

Toilet seats have a maximum weight limit, and it usually mirrors the weight limit of the toilet, at about 300 pounds. However, some seats fare better than others, with flimsy plastic seats prone to cracking and breaking.

Stainless steel seats have the highest weight tolerance because they are designed for use in public toilets where the size and shape of people are non-determined, so they need to be robust.

Feedback: Was This Article Helpful?
Thank You For Your Feedback!
Thank You For Your Feedback!
What Did You Like?
What Went Wrong?
Headshot of Mark Weir

About the Author

Mark Weir

Mark spent 24 years working in real estate, so he knows his way around a home. He also worked with contractors and experts, advising them on issues of planning, investments, and renovations. Mark is no stranger to hands-on experience, having renovated his own home and many properties for resale. He likes nothing better than seeing a project through to completion.