toilet seat

Toilet Seat Sizes

You might be wondering about how to choose the best toilet seat size. Are there standard measurements for different toilets?

What are the benefits and drawbacks of the different options? Thankfully, learning about toilet seat sizes is fairly simple.

Or maybe you’re wondering how to replace a toilet seat. If that’s the case, you don’t necessarily need to buy an entirely new toilet.

You just need to get the right seat for your model’s size. In this case, it’s important to know how to measure your toilet seat and purchase one with the proper dimensions.

Standard Sizing

toilet seat standard sizing

While not every toilet seat is standard in dimensions, there are some standardized measurements that you should be aware of. These measurements are codified into nearly any modern toilet.

You’re unlikely to find any toilets that don’t fit these measurements, and if you do, they’re likely older models that were created prior to standardization.

Your toilet seat should come with two bolts that secure the seat to the bowl itself. No matter what shape or dimensions your toilet has, the distance between these holes tends to be 5.5 inches.

You can always measure on your toilet to double-check, but it’s very unusual to have a different width.

Toilet bowls also tend to be very similar in width. While there is no official standard, almost all models are around 20 inches wide.

Variance is usually less than half an inch. Again, you can measure the width of your toilet bowl to double-check, especially if you have an older or unusual model.

Non-Standard Seats

There are rare cases in which you’ll find that your toilet doesn’t comply with standard sizing. This can limit your choices of seating somewhat.

It gets even more complicated when your toilet is older or an antique, as finding the right seat dimensions can be difficult.

It’s best to measure all the dimensions of your toilet to make sure you have the right information about the seating.

If you know the exact model of the toilet, you can find out whether the manufacturer sells seats sized for that specific model. Similarly, if you only know the manufacturer, you can see whether their website has any section for non-standard toilet seats.

Then you can browse until you find one that matches your dimensions.

In some cases, you might not know the manufacturer. Or in the case of older models, the manufacturer might be a defunct company.

At this point, you’ll have to look online for a non-standard toilet seat built to your specifications. You might also need to put in a special order with a local plumbing or hardware store.

Toilet Bowl Shape

toilet bowl shape

The biggest factor at play with different toilet seat sizes is the shape of your toilet bowl.

Toilet bowls come in two basic shapes: round and elongated. A round seat will not work for an elongated bowl, and vice versa.

So it’s important to know which type of seat you have.

If you’re in the market for a new toilet, it also helps to understand the differences between elongated and round bowls. Each type has its own unique benefits and drawbacks.

Elongated Bowls

Elongated toilet bowls have become increasingly common over the past few decades. Instead of having a round shape, they tend to be oval.

The seats for an elongated toilet bowl will also be oval in shape. They tend to be a minimum of 19 inches long, while they’re a maximum of 15 inches wide.

An elongated bowl will typically have about four more inches in length than a standard round bowl. The biggest advantage of the elongated bowl is that the seat has more surface area, which makes it appeal to men and larger women.

The added comfort sometimes makes them more accessible.

However, those four inches in length can be detrimental if you have a very small bathroom. They might take up too much space.

In addition, a large toilet can have a negative impact on accessibility in a small bathroom. There’s less room to maneuver for people with mobility issues.

Round Bowls

While elongated bowls have become more popular in recent years, most bathrooms use round bowls as their standard. When you do the rough-in for a toilet, in many cases, you’ll find that the bathroom is sized to fit a round bowl more than an elongated one.

Despite the name, round toilet seats aren’t always perfectly round. They can also be oval in shape.

Their biggest defining factor is that they’re much smaller than elongated seats, so they work better in a compact space.

The seats might be anywhere from 13 to 15 inches in width. They’re usually at least 16 inches in length, but might be up to 18 inches instead.

Most older toilets will use a round bowl. In these cases, you’ll need a round seat to fit on top.

An elongated seat will jut out awkwardly and won’t properly cover the rim of the toilet bowl.

Round bowls can sometimes be cleaned more easily than elongated ones. This is because they’re smaller and more compact, which makes them easier to scrub.

They may also have more uniform ports around the rim. These components allow water to flow into the toilet bowl with each flush.

With all of that said, round toilet seats aren’t the most comfortable to sit on. If you have digestive issues that require you to spend a long time in the bathroom, you might experience more fatigue with a round seat.

Since round toilet seats are smaller than elongated ones, it’s common for them to be easier to afford.

Measuring Your Toilet Seat

measuring toilet seat

Since different toilets range widely in size, it’s important to get the right seat dimensions. If you need to replace your toilet seat, you’ll need to take a few measurements.

Fortunately, the process is fairly straightforward.

You’ll only need three basic measurements: the length, the width, and the post holes. Let’s take a look at how to measure for each.

Seat Length

Your toilet seat length has the highest amount of variability. The length could vary by more than eight inches, depending on whether you have a small round bowl or a long elongated one.

So this is the most important measurement you’ll take.

You want to start between the post holes. These are the holes on the back of the toilet bowl where you’ll secure the seat.

Measure in a straight line from the midpoint of the holes to the very front of the toilet.

You should measure to the outer edge of the bowl. If you stop at the inner edge of the bowl, your measurement will be too short.

The length of your toilet bowl will also tell you whether you have an elongated or round model. Elongated models tend to be longer than round ones.

A round model usually has a maximum length of 18 inches, while elongated ones can be up to 22 inches.

Seat Width

The next step is to measure the width of the seat. Most toilets are relatively similar in width.

They tend to be about 20 inches across, give or take around a half-inch.

However, there are some models that might be smaller. You might find that your toilet is only 13 to 15 inches across.

That goes especially for toilets sized for children.

Round toilet seats tend to be slightly wider than elongated ones. But as mentioned, it’s rare for them to deviate much from the 20-inch measurement.

Make sure that you measure across the widest part of the toilet bowl. This is how the width is determined; when you see toilet seat dimensions online, they’re referring to the widest point.

Post Holes

The post holes are the most standardized of your toilet seat measurements. But it’s a good idea to take a measurement just to be sure.

Your post holes are found along the back edge of the toilet bowl. They’re the holes where you place the bolts to secure your toilet seat.

It’s important that you get a toilet seat with the same distance between the holes as your toilet model. Otherwise, you won’t be able to secure the seat at all.

Since the distance between the holes is relatively small, you don’t even need to use a tape measure. A ruler will work fine.

Put the ruler against the inner edge of one hole and measure the distance to the other inner edge. Then measure the distance between the outer edges as well.

These two measurements might be more than a half-inch difference. The most important measurement is between the outer edges, as this is the widest gap.

The standard gap between the post holes should be 5.5 inches. If your measurements are close to this, then any standard toilet seat should work fine.

But if you have a much larger or smaller gap, you might need to order a special toilet seat to make sure you can secure the bolts.


Since there are different toilet bowl sizes, there are also different toilet seat sizes. Before you go shopping, you need to know whether your toilet bowl is elongated or round.

You also need to have a good measurement of the dimensions of your seat.

Elongated seats are often more convenient and comfortable. However, they are harder to clean, and they take up more room.

People remodeling a small bathroom might prefer a round seat, which is much smaller and more compact.

Overall, as long as you have the right measurements, you shouldn’t have much trouble finding the right toilet seat. While it’s easiest to purchase one from your toilet’s manufacturer, any seat fitting the dimensions should work.