A toilet seat is 18″×15″. It is slightly elongated. On the market there are two styles: "standard" and "elongated". It seems to be neither.

I purchased two toilet seats that seem also intermediate, but they both turned out to be 15″×14″.

Is measuring the lengths of the two axes of the kind-of-ellipse the right way to buy replacement toilet seats? What is the right way to measure a toilet seat for replacement?


  • If you have a non-standard bowl size the only relevant aspect is the dimension. What's the question?
    – isherwood
    Commented Jan 16 at 20:01
  • 2
    Nothing beats taking a piece of cardboard and tracing it.
    – Nelson
    Commented Jan 17 at 5:23
  • 1
    @Nelson I think this nails it. They may all look like ellipses, but none is an actual ellipse. In particular, two may have the exact same long axis and short axis lengths, but still not fit one to the other.
    – Sam7919
    Commented Jan 17 at 15:10
  • 1
    I've removed your "wondering" musings because they're really got nothing at all to do with the question and attempting to address them would venture well into the realm of "opinion" which is off-topic.
    – FreeMan
    Commented Jan 17 at 15:30

2 Answers 2


Take the existing seat to your local big-box or plumbing store and look for one that matches, as closely as possible, the size and shape.

Not everything has to be purchased online - nothing beats getting your hands directly on the product before plopping down cash and walking out the door.

  • I wholeheartedly share your sentiment, but I can assure you that I walked into several branches of each big and small hardware stores nearby. I was eventually led to a specialized, and independent, plumbing store, who still did not stock anything resembling a suitable replacement. They did, however, provide me with the phone number of the manufacturer. Lo and behold, it can be obtained, and, yes, online only ("the generics are not suitable"). Is it well made? Yes. Would I rather lock myself into a Gillette-like provider of toilet seats? Definitely not.
    – Sam7919
    Commented Feb 16 at 18:03
  • Hmm. Overpaying for toilet seats...is like flushing money down the toilet. (Sorry, couldn't resist.) Commented Feb 16 at 18:27
  • Sorry, @Sam7919, that really draws a vacuum. In order to buy a generic toilet seat, you'll have to replace the whole toilet. For the short term, buying seats from the mfgr is probably cheaper. When you do next replace the toilet, make sure it'll take any old seat. (As an example, I've purchased 3 Toto toilets. They didn't come with a seat at all, indicating that just about anything would work.)
    – FreeMan
    Commented Feb 16 at 18:38
  • @manassehkatz-Moving2Codidact You assumed that? It's actually priced at the bottom of the scale, compared to the prices at the Big Boxes, but with at least some of the bells & whistles of the 2.5x as expensive models (with slow-down seat and cover, whatever that feature's called). The only catch is that it must be purchased from a specific supplier.
    – Sam7919
    Commented Feb 16 at 18:49
  • @FreeMan FWIW, it's actually an excellent seat, never pinching a nerve, for one unexpected feature helpful for those with little to no "padding" on their own.
    – Sam7919
    Commented Feb 16 at 18:51

In theory at least, there are 4 things that matter:

  • Length (front to back)
  • Width (left to right)

Length and width should be such that the seat covers the entire "ellipse" of the top of the bowl.

  • Distance between the "bolt" holes
  • Position of the "bumpers" (for lack of a better term) that keep the seat level when down and keep most of the seat from actually touching the bowl.

If you are really not sure then you have three practical options:

  • Lookup by manufacturer (usually easy to find) and model (often not so easy to find)
  • Take the old seat to a store. Really. Then you can easily compare to various options.
  • Trace the bowl - entire inner and outer "ellipse" and position of "bolt holes". Take the tracing to a store. Then you can easily compare to various options.

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