Are Toilet Tanks Universal? Get the Best Fit

If you need to replace a toilet tank that is cracked or damaged, then you may run into a common question: Are toilet tanks universal (i.e. standard sizes)?

Toilet tanks are not universal. Toilet tank sizes vary depending on which of the three flushing systems you have; dual flush, gravity, and pressure-assisted. Generally, toilet tank sizes are universal within these flushing system categories, unless you have a custom toilet. 

Further on in this article, you will find information to help you find, purchase, and install a new toilet tank that is the perfect fit for your toilet. Let’s get to it!

Are Toilet Tanks Universal?

In short, toilet tanks are not universal because there are three different types of toilet flushing systems which have different tanks. However, toilet tanks that have the same flushing system are interchangeable with one another.

To really understand the differences between these toilet tanks, we need to learn about each type of flushing system.

Types of Toilet Tanks

To understand what type of tank you have, first, you need to know the kind of toilet you have. Listed below are the three toilet varieties available to consumers. The tank you need is going to be specific to the type of toilet you own.

1. Dual Flush Toilet

In this type of toilet, the flushing mechanism is found on the top of the tank in the form of two buttons, one for low flow and one for high flow. These control how much water is used to flush the toilet.

So, if you have a toilet that has two flushing options, then make sure that you look for tanks that are compatible with dual flush toilets when you go shopping for a replacement tank.

2. Gravity Toilet

Gravity toilets are probably the model of toilet that is most frequently used in homes today, so there’s a pretty good chance that this is the type of toilet you have.

Gravity toilets flush by using gravity (hence the name) to facilitate the movement of water from the bowl into the sewage system. 

3. Pressure Assisted Toilet

While similar in build to a gravity toilet, this type differs in that a mechanism in the tank pushes the water down the pipe into the bowl and then through to the sewer. 

Knowing the type of flushing system on your toilet is an important step, but you’ll also want to take some measurements to make sure everything will line up.

How To Figure Out What Kind Of Tank You Need

There are two ways you can figure out what kind of toilet tank you need. You can find your brand and serial number or you can manually measure your tank. Let’s go over each one.

By Brand and Serial Number

The first thing you need to do is figure out what brand of toilet you have. You can find this either inside the lid of the tank or down right behind the bowl like below:

Are toilet tanks universal sizes

After you have the brand, then you’ll also want to know the serial number. For example, I found the serial number for my toilet on the inside of the toilet tank here:

Now that you have the brand and serial number, you can Google it. If you have a recent model of toilet you’ll likely be able to find replacement parts online. But if the model is old or discontinued it might be tough to find.

You can also go into a local hardware store or home improvement store and ask an associate for help. If you tell them the brand name and the serial number, they’ll likely be able to help you find the right replacement tank.

Manually Measuring the Tank

If you’re not confident that you’ll be able to easily find a perfectly fitting replacement tank for your toilet or you can’t find the serial number, then you may want to take a few measurements.

To do this, you’ll need to grab a measuring tape, a pen, and some paper.

You will need to measure the following distances:

  • Depth of the tank
  • The length of the tank
  • The width of the tank

You’ll also want to take a quick measurement of the pipes and fixtures. When you shop for a new tank, you will need to make sure the pipes and fixtures you have fit. Otherwise, you will need to replace those as well.

Now, what about the sizes of the tank bolts (and bolt holes)?

Are The Tank Bolt Sizes Standard?

Just as the tanks vary, so do the bolts and bolt-hole sizes.

Similar-sized toilets may share bolt and hole sizes while a custom toilet may use unique sizes.

But usually, the size of a bolt is 1/4th inch or 5/16th inch.

The size of the bolt hole will match the size of the bolt. When you go to take measurements of the tank, look at the bolts. If they are not too eroded, you’ll be able to read the size right off the markings on the bolts.

Side note: If you also intend to replace your toilet seat, then you’ll need to consider toilet seat sizes as well.

Where To Purchase Your New Tank

Once you know what you need, where do you go to buy it? Check out a few of the stores below.

If you feel uncomfortable with online shopping, then a trip to the local hardware/home improvement store is in order. If they do not have the tank you need, they can probably order it for you. 

You can also order online for pick up in-store if the store of your choice offers that service. A second option is in-store shopping and having the toilet tank delivered to your home.

If you’re planning to move the toilet tank (or a full toilet) yourself, then you’ll probably also want to consider how much toilets weigh.

Common Toilet Brands 

When it comes to brands, you’ll usually just want to go with the brand that made the rest of the toilet you’re repairing.

But if you want some extra guidance on the top toilet brands on the market, here’s a brief list of the leading manufacturers.

  • Kohler
  • American Standard
  • Glacier Bay
  • AquaSource
  • Sterling
  • ToTo

How Do You Install Your Toilet Tank

After you’ve purchased your toilet tank, you’ll need to know how to install it properly. There’s a video below that walks through the process of installing a toilet tank.

If you’d rather read the steps, there’s also a step-by-step guide for how to install a new toilet tank on

Note that the video above doesn’t cover how to properly remove an old toilet tank. However, the article above from does cover that topic.

In Conclusion

When asking the question is a toilet tank universal, the short answer is no. While in certain brands they can be interchangeable, the overall consensus is that your toilet tank is fitted to your toilet model.

When looking to purchase a new tank, you need to learn the measurements and model number. This helps you to find the correct replacement toilet tank.

And if you find the task of replacing the toilet tank to be more complicated than it previously seemed, there is no shame in seeking professional help. Call a plumber to install your new toilet tank if you feel it is needed.

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