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How to Measure a Toilet Seat

Last Updated on
Last updated on

How to Measure a Toilet Seat

Toilet seats get a bad rap for being a bacterial breeding ground, but the average keyboard has over five times more bacteria than the average toilet seat. (1)

Even so, we all like a nice, clean toilet seat. When a toilet seat starts to show signs of age, it gives the entire bathroom a lousy vibe.

If you’re ready to replace an aging or broken toilet seat, you’ve come to the right place. This article will teach you how to measure and install a new one.

Toilet Seat

Related: The Best toilets for your home

Remove the Old Seat

Measuring the bowl correctly for a new seat is more important than you think. The main types of toilets are round and elongated (2), but there’s more to it than that.

There are many widths, types, and lengths of toilet seats, and not all of them are compatible with every bowl. For that reason, unless you want to change your bowl too, make sure you measure carefully.

Before you start measuring, you’ll want to remove your old toilet seat from the bowl. Doing that will make it easier to use a standard tape measure.

If your toilet seat has plastic nuts and bolts, you’re in luck. They can’t corrode and will be easy to remove.

Many seats have bolt covers that can be popped off with a flathead screwdriver. Hold the bolts from the top and use a wrench with a deep-well socket to loosen the nuts from the underside of the bowl.

Once loose, you can continue unscrewing them with your hand.

If your metal bolts are corroded, that might take a little extra work. You may have to extend the handle on your wrench to get more torque. If they’re thoroughly corroded, you may even need to break them off.

Because of the moisture-laden nature of the bathroom, metal bolts can rust and be quite difficult to remove. Spray metal bolts with a penetrating lubricant and allow this to soak in for several minutes before attempting to remove the bolts on the toilet seat.

Johnny Snap from Snap Goods

Basic Measurements

With the old toilet set removed, you’re ready to start measuring.

  1. Start by drawing a line between the bolt holes in the back of the bowl’s rim and mark the middle of the line. You can do this with a dry erase marker.
  2. While you’re at it, note the distance between the bolt holes. The standard distance is 5 ½ inches but some bowls might have a different spread.
  3. Hold a measuring tape to the mark in the middle of the bolt holes and measure to the farthest point on the rim at the tip of the bowl. Note the length.
  4. Next, hold the tape measure parallel to the bolt holes and measure the widest point on the bowl.
  5. Finally, if you’re ordering a specialty seat, you should measure the distance between the bolt holes and the tank. If you’re buying a standard seat, this isn’t necessary as there’s nothing to add behind the bolts.

If you don’t have a standard bowl, you may have to special-order a toilet seat from the manufacturer. Square toilet seats are an example of this.

Ready to Purchase

Now that you have your width, length, and bolt spread, you’re ready to pick out the perfect seat.

Ideally, you’d get to see and measure a toilet seat before you buy it but if you’re buying online, that’s not possible.

Generally, manufacturers won’t provide much information on the size of the seat. Some are better than others about it, though.

Mostly, you’ll get the length measurement for the round variant of a toilet seat and one for the elongated. Therefore, you’ll need to do a little sleuthing.

Online retailers are notoriously bad about giving you all the details about a toilet seat. It’s up to you to find out what you need to know.

When you find a toilet seat that you like, go to the manufacturer’s website. There, find the model, and you’ll almost always find a specification sheet for it.

The spec sheet will have much more information than the online retailer, including the exact measurements. You’ll also find more valuable details, such as the hinge material, type of ring bumpers, and others.

Install Your New Seat

Once you pick out a seat that fits your bowl and it finally arrives, you’re ready to install it.

Simply reverse the process you used to remove the old toilet seat to install the new one. Line it up carefully with the bolt holes, place the bolts and tighten them firmly but not overly so.

Tightening the nuts too much can result in a crack or chip on your bowl, especially if they’re metal. (3)

If the seat has metal bolts, it’s a good idea to slather them in a corrosion-blocking lubricant. They’ll be entirely out of sight so it won’t impact your decor, and you’ll know that it can easily be replaced many years later.

Measure Twice Buy Once

You’re ready to replace your broken, faded, or just plain ugly toilet seat.

While there are two main standards for toilet seats, it doesn’t hurt to make sure you’re getting the one you need.

After removing your old seat, it only takes a minute to get the width, length, and bolt spread of your bowl. Then, it’s just a matter of finding that perfect seat.


  1. The Healthy. 2020. 15 Everyday Items Dirtier Than A Toilet Seat. [online] Available at: <> [Accessed 9 March 2020].
  2. Kohler US. 2020. Toilet Seats Guide: Bowl Shape | Bathroom | KOHLER. [online] Available at: <> [Accessed 9 March 2020].
  3. The Healthy. 2020. 15 Everyday Items Dirtier Than A Toilet Seat. [online] Available at: <> [Accessed 9 March 2020].

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