How to Measure a Toilet Seat? (Width, Length & More)

Written by

Paulk Webb


Freddie J. Hagopian

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how to measure a toilet seat

You have to replace a broken or rattling toilet seat. Before looking for a replacement in the hardware store, you need information about the exact toilet seat sizes.

Oftentimes, you can find such information from the manufacturer, attached with the toilet instructions when you bought it. But, worry not if you have a measuring tape and know exacly how to measure a toilet seat.

Step-by-Step to Measure a Toilet Seat

Learn to measure for a new toilet seat in this article before heading out to the home improvement store. Be guided so you won’t forget even a single detail to get an exact replacement of the same size.

Toilet sizes can vary due to the toilet seat materials and shapes.

The round or slightly circular toilet is mainly considered toilet seats universal. An oval-shaped seat for an elongated bowl is also common.

Apart from the elongated and round toilet seat, there are D-shaped and square or rectangular. There’s also a U-shaped or open toilet seat which is common in public toilets in the USA.

Furthermore, they have an array of seat sizes.

The good news is, for whichever shape, you can get the toilet seat measurements, including:

  • The toilet width
  • The toilet length
  • Mounting distance between the bolts near the back of the toilet seat

1. Measure the toilet width


Bring the tape measure to the center of the toilet and measure the width of the seat. You may find out the measurement by placing one end of the tape on one side and drawing the tape to the other.

Make sure you jot down two measurements, the inner width and the outer width of the toilet seats.

  • An elongated toilet seat standard’s inner width is 8 ⅛ inches and its outer width is 14 3/16 inches.
  • Meanwhile, the round toilet’s measurements are 8 7/16 and 14 5/16 inches, respectively.

Indeed, the sizes will be different for various models of these two toilets, that’s why you need an exact measurement of your own toilet.

2. Mesure the toilet length


In the case of length, you have to place your tape measure in the middle of two bolt holes. Then let the tape stretch until the outer edge of the seat’s scope to get the length.

The length of round bowls is 16.5 inches while the elongated bowls have 18.5 inches. With these measurements, elongated toilets have more space to sit on.

3. Mesure the mounting hole distance


You have to measure the distance between two mounting holes. The standard distance is 5.5 inches for both types of toilets, and the midpoint is 2.75 inches.

Important notes:

  • When you have a raised toilet seat

There’s no need to include toilet seat thickness in your measurement unless it’s a raised toilet seat. This type of seat is for people who struggle with leg fatigue and weakness. It’s usually 4 to 6 inches thick or 101.6 to 142 in mm. The thickness helps these individuals to have a comfortable sitting position.

  • No room for mistakes

Since there are different size toilet seats, you have to be thorough when measuring the toilet seat dimensions. Make sure to double-check to ensure that you get the exact numbers.

Frequently Asked Questions


What is the standard toilet seat size?

The standard size is based on the toilet bowl shape. The length of an elongated toilet seat is 18 to 19 inches, and it’s 16 to 17 inches for the round one.

They’re the common seat shapes with similar widths and bolt spread. The width is 14 to 14.5 inches, while the bolt spread is 5.5 inches.

Meanwhile, here’s the list of the common-size toilet seats in the UK.

  • Width – 13.75”; length – 15.75” to 16.14”
  • Width – 14.17”; length – 16.14” to 18.90”
  • Width – 15”; length – 16.14” to 18.90”
  • Width – 15”; length – 16.14” to 18.90”

Some manufacturers develop adjustable hinges for the seat. If they have plastic covers, you can easily make adjustments in their place. Rotatable hinges were invented to double the distance of bolt holes if needed.

How do I know my toilet seat size?

To get your toilet seat size, you have to measure the length, width, and space between the mounting holes.

Then, you can look up the models of your toilet and browse through their collections to find a similar-size toilet to double-check your measurements. All toilet companies, like the toilet seat B&Q, Kohler, etc., all provide clear information on their websites.

Why is it important to get the toilet seat measurements?

The importance of having the exact toilet seat dimensions is obvious, especially when you need a toilet seat replacement.

You shouldn’t take for granted the need to measure as there are consequences of the wrong size toilet seat. A long toilet seat is wobbly, so it causes discomfort. If it’s too short, it can’t cover the edges. It causes instability and discomfort at the same time.


There are only a few steps on how to measure a toilet seat. You’ll find them with ease when you have the right tools to assist you. Though they are simple steps for you, you have to pay attention when measuring, as preciseness is crucial.

If you’re careless about the measurements, you’ll end up with a wobbly and unstable toilet seat. So, width, length, and space between the bolt holes are also important details. The relevance of the seat’s thickness applies to the raised type.

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