How to measure the toilet flapper | 3 Simple Ways

The flapper is the most essential part of the toilet flush. It controls the flush power and water seal of the toilet tank. 

Toilet Flapper is the cheapest tool and is worn out often. So it is crucial to change it frequently. But before replacing it with a new one, you have to know the correct measurement.

Today I discuss how to measure the toilet flapper and how to install it.

What is Flapper? Toilet flapper types

A toilet flapper is a rubber flap that is installed in the flush valve of a toilet. It is designed to seal the opening between the tank and the bowl to prevent water from leaking out. 

The flapper rises when you flush the toilet, allowing water to enter the bowl. The flapper returns to its original position when the tank is refilled and shuts the entrance.

The universal toilet flapper is designed to fit most major brands of toilets (including American Standard, Kohler, TOTO, Crane, and Mansfield).

Types of Toilet Flapper

There are three types of toilet flappers: 

1.   The conventional flapper– Conventional flappers are cheap and easy to replace, but they’re also the least efficient type of flapper.

2.   The float cup flapper– Float cup flappers use a float ball to detect when the tank is full and, therefore, conserve water (although, like conventional flappers, they tend to wear out after only a few years).

3.   The expanding flapper– Expanding flappers aren’t nearly as efficient as float cup flappers but make up for it by lasting almost forever.

Toilet Flapper Size

When it comes to toilet flappers’ size, there are a few things you need to keep in mind. 

The most important thing is getting the right size for your toilet. You can find the right size flapper by measuring the opening of your tank. 

Most tanks have an opening of 2 1/2 inches, so you’ll want to get a flapper that is that size or smaller.

2 Inch Flappers:

A flapper is a rubber or plastic plug that fits tightly into the drain of your toilet. 2-inch flappers that work very well for strong flushes and economizing water usage.

3 Inch Flappers:

A 3-inch flapper gives your tank more water to work with than a 2-inch flapper does, resulting in a stronger flush that uses less water. This makes it better for areas where stricter conservation efforts are in place (such as California). 

A 3-inch flapper will give you the strongest flush possible until you’re ready to replace your toilet entirely. 

4 Inch Toilet Flappers:

4-inch flappers are not as standard as 2 or 3-inch units, but they still exist.

4-inch toilet flapper has in the American Standard Champion series. Laeger the flush valve greater flushing power.

How to measure the toilet flapper?

The height of the toilet flapper is very important for a good function.

A too low or high toilet flapper can cause a water leak and damage your properties. 

Simple tricks to measure the toilet flapper

There are many ways how to measure the toilet flapper. 

best way to measure a toilet flapper


It is easy to measure the flapper by using a standard ruler. 

However, this method is not too accurate because it can be difficult sometimes to align accurately with the holes in the plastic hinge that holds the flapper valve in place.


Another method is using a metal ruler. The valuable thing about this instrument is that it’s easier to line up with the holes in the plastic hinge without tilting or turning the flapper valve itself. 

Take note of these measurements because they are essential! Even if you have an old house, newer toilets should use ones measuring 7 inches +/- 1/4 inch.


Here’s another trick that uses simple household items; a piece of paper, tape, and water. 

You need to cut out or tear apart a square sheet of paper. Make sure the square is thicker than the height of the toilet flapper (usually about 1/2 to 3/4 inch thick).

The next step is to attach the piece of paper to the interior of your toilet bowl.

Make sure it completely adheres to the surface of the bowl, as this will be used as a water-resistant barrier against spills and splashes. 

You’ll also want to check for wrinkles or bubbles in the tape to ensure that it creates an even seal all the way around the paper barrier.

This will allow it to create a larger section for measuring. 

You might think that measuring at this point would be too difficult because there’s still some water sticking on top of the paper barrier. 

However, don’t worry about it! 

How do I know if I have a 2 inch or 3 inch toilet flapper?

Without knowing the brand and type of your toilet, there is no way to tell whether you have a 2 inch or 3-inch toilet flapper.

However, you can measure the size of your current flapper to get a general idea. 

Most 2 inch flappers will be around 6 inches in diameter, while most 3 inch flappers will be approximately 8 inches in diameter. 

If you’re not sure which size your flapper is, it’s best to consult with the manufacturer or your local hardware store.

Are most Toilet Flappers 2 or 3 inches?

Toilet Flappers come in several different sizes, including 1.6″, 2″, 2.5″ and 3″.

The most common flapper size is the 2-inch flapper used on all of our high-performance toilets

The 3-inch flapper may be installed in huge tanks or extremely hard water conditions to help keep your tank filling quickly after each flush. 

Tip for how to choose the right toilet flapper

Almost all the toilets use the same flapper, so if you have a problem with your toilet, you must know what is wrong before looking for the right flapper. 

Finding the right toilet flapper at a local home repair store is often an overwhelming experience. 

With so many options, it’s tempting to choose the one that looks or sounds best. 

However, you should look past the flashy colors and advertisements for maximum performance and satisfaction when choosing your replacement rubber flapper. 

A well-insulated tank makes the most of every flush by minimizing heat loss during each cycle, saving water in the process. 

As a result, it’s best to choose a color that matches your existing tank lid cover rather than what might have been on there before. This will ensure that no additional insulation is lost through gaps around the new flapper or lid cover edges.

Lightweight and economical, this color-matched rubber flapper is designed exclusively for use in insulating tanks with an insulated lid cover.

How to Check Toilet Flapper

A toilet flapper is a valve that controls the water flow from the tank to a toilet bowl. 

When the flapper is open, water flows from the tank to the bowl, and the toilet flushes and the flapper is closed; water is cut off from the bowl, and the toilet does not flush.

To check if your toilet flapper is full, you must remove it from the tank. 

Once you have removed it, you will see if it is full or not. If it is full, you will need to clean it out and put it back in place. 

If it is not full, you have some other issue on your hands.

How to replace a toilet flapper

A leaking toilet is not something you want to play around with. Luckily, the leak itself isn’t too hard to fix – neither is replacing the flapper! Check out this step-by-step guide on how to replace a toilet flapper!

Step 1: Buy A New Flapper

Buy The Flapper Since your current toilet flapper already broke. You’ll need to buy a new one before you can fix your toilet. 

You can find these in hardware or home improvement stores, and they usually cost between $2 – $10. 

The flapper often has the brand name stamped on it; for example, if yours says “Korky,” then make sure you get another Korky flapper!

Step 2: Remove The Tank Lid

Almost all toilets work the same way! If you’re not comfortable disassembling your toilet entirely, at least remove the tank lid so that you can take out the old flapper.

Remove the screws that hold the tank cover in place, then lift it up to expose the workings of your toilet. 

You can now see where the flapper is attached to your toilet; carefully detach this by lifting up on the chain that’s holding it together.

Step 3: Disconnect The Chain

The broken flapper should still be held onto the rest of the tank with a chain. This must be disconnected before a new one can be installed.

Carefully pull apart any wire clips connecting the old parts together; disentangle them until they’re completely separated.

Step 4: Attach The New Flapper

If all goes well, following these steps will result in an empty space on top of your toilet tank where a new flapper can now be attached. 

Carefully set the new flapper on top of your toilet tank – it should fit right where the old one was – then press down on it until it locks into place. 

Slowly pull up on the chain that’s holding it together until there’s enough slack for you to tie a knot in between both ends of the chain. 

After making a loose knot with the two ends of this chain, pull them tightly towards each other, so they stay bound together properly. 

If this doesn’t work the way it should, you may need to tighten your knot more – or possibly untie it entirely and try again.

Step 5: Reattach The Flapper Chain

Now that your new flapper is attached, all that’s left to do is reconnect the chain that holds it together! When connecting the clip, make sure you’re only hooking one side of the chain together at a time. Otherwise, you may not be able to connect your two ends properly.

Step 6: Reattach Tank Cover and water supply line

And finally, once all of your attachments are set up correctly, reattach your tank lid by screwing each of its screws back into place. 

Here’s how to change a toilet flapper!

You can now fix the most common toilet leaks without calling a professional. It may take some time and effort, but it’s definitely manageable if you follow these steps carefully; in most cases, you shouldn’t need any extra tools either!

Read More- What to do When Toilet run after replacing the flapper

Best Toilet Flapper

2” Toilet Flapper- 

How to measure the toilet flapper | 3 Simple WaysHow to measure the toilet flapper | 3 Simple Ways

Fluidmaster universal water saving 2″ inch flapper

How to measure the toilet flapper | 3 Simple WaysHow to measure the toilet flapper | 3 Simple Ways

Fluidmaster Water-saving 3” toilet flapper

How to measure the toilet flapper | 3 Simple WaysHow to measure the toilet flapper | 3 Simple Ways

American Standard 4″ Toilet flapper with flush valve

FAQs Related to Toilet Flapper

Q1. How do you know if the flapper needs to be replaced?

If your flapper needs to replace, locate the following signs
~Water always Leakage from the tank to bowl
~Flush is slow
~Tank water not fill properly
~Sometimes water leaks and drops into the floor
~Flush is not strong as before
~Toilet tank takes a lot of time to refill with water after flush.

Q2. How do you measure a flush valve?

Flush valves are usually installed at the height of 650mm. Please measure from floor level to the center of the flush valve/tank connection when measuring.
The width will be measured in the fully open position. If you do not have a tape measure handy, there is easy to find out the correct size before purchasing.
Simply follow these instructions:
1) Determine which imported toilet model you wish to purchase.
2) Flush Valve Usually comes under 2 inches, 3 inches, and 4 inches, only the American standard champion series.
3) Know your flapper diameter it determine the flush valve dimension also.

Q3. How long does toilet flapper last?

Toilet flapper can last from half a year to several years. Toilet normally requires replacement every 2-3 years. 

Q4. How do I know if my toilet flapper is bad?

If you have to jiggle the handle or hold down on the lever for your toilet to stop running, this means that you need to replace your flapper because it is terrible.
If you notice a delay in refilling the tank after flushing the toilet, it’s probably time for a new one as well. 
In many cases, if water continues to run from your old flapper without being triggered by the float ball, it is an indication that something else might be wrong. 
Even if there are no other symptoms, a bad flapper will eventually simply wear out and require replacement.
The rubber part inside tends to break down over time and cannot be repaired!

Q5. Do I need a new Flapper?

A leaky toilet is one of the most annoying household problems. It wastes water and money as you have to keep on using your water bill as a source to pay water bills. 
And, as if this isn’t enough, it is inconvenient. It makes people feel very embarrassed when guests come over, and the flush is not done correctly. 
The most common reason for a toilet leaking or not flushing is when the flapper needs to be replaced. 
Yes, due to constant use, they get worn out after some years or months, so you must check whether this is causing your leakage problem. 
The other thing that can cause a leaky toilet is something wrong with either chain linkage or float level. Please read our article about how to fix these problems here.
The main reason people need to replace the flapper. 
So if you locate yourself in this situation, please don’t wait until you have guests or an emergency, but instead, get hold of a new flapper as soon as possible.

Leave a Comment