If you ask most people what a toilet flange is, they probably don’t know. At Green Energy Mechanical Inc, we have encountered many clients who have no clue about toilet flanges. Therefore, when their flange begins to misbehave, they don’t know what to do or buy.

The flange usually hides beneath the toilet and connects your unit to the sewer line. If this part is not properly functioning, you might find your toilet leaking at the base or becoming shaky. Therefore, you need to involve our plumbers to replace it with a new one. Read on to help you understand the different sizes and types of flanges available to help you know what to purchase for your toilet.

Sizes of Flanges

Flanges have four main sizes.

Four by Three

This is the market’s most common size of flanges and fits most toilets. The top part has a diameter of four inches, and the bottom part has a diameter of three inches. The top opening connects to the toilet, and the bottom part attaches to the drain that leads to the sewer line.

Three by Three

These flanges have equal diameters on both the top and bottom parts, and they are very easy to fix. However, you should not install this if your toilet’s base has a diameter of four inches since it will make the toilet unstable and leaky. Ensure the dimension of your system fits exactly this size of a flange to allow for effective drainage of waste.

Push-Tite Flanges

The push-tite type of flange is usually very friendly for heavy plumbing. These do not have a specific size, and you only need to press the opening to fit onto the floor securely. You should also push the lower part into the drainpipe to fit in the gasket entirely inside the line. The benefit of using this kind of flanges is that it is very durable and can withstand harsh chemicals and heat.

Odd Sizes

Odd-sized flanges are those that have unusual sizes that are not in any of the above categories. You may find flanges with diameters from 3.5 inches to 7.5 inches, which require attaching an extension to help them fit securely. The extension kit makes it fit into the standard piping perfectly so that the toilet’s waste will not leak through any extra spaces. When you go to look for the different sizes of flanges, you have to confirm the size of your toilet base. With our work experience, we can easily help you identify the size, and we can also come with the flange when we come to perform the replacement.

Shapes of Toilet Flanges

Apart from identifying the size, you also need to know the shape you need for your toilet flange. The forms may not differ much, but each fits differently depending on the length and shape of the base. It is essential that you consult our trained professionals to help you determine the best shape for your toilet to ensure complete sealing of the toilet base.

Regular Flanges

Most flanges are circular at the top and bottom since most plumbing systems have this shape. The regular ones have a length of about 5 inches, which helps create a distance from the sewer line to prevent foul odors from ascending to the toilet. Since most drain openings are circular, these standard flanges best fit most bathrooms.

Deep Seal Flanges

Deep seal flanges are similar to the regular ones but only have a difference in length. As the name suggests, they go deeper into the drainpipe, creating a better seal to prevent the foul smells from reaching the bathroom. Most of these flanges are about 12 inches long, which is enough room to go further down the drain.

Offset Flanges

Offset flanges bear this name because they can adjust to various toilet floor situations. If your toilet outlet has an awkward position in which the regular flanges cannot fit, then you require to get an offset flange. While you may not readily know if you need an offset flange, our experts at Green Energy Mechanical Inc have worked on many toilets and can identify any unusual placement within minutes.

We mostly recommend this type if the drainage is at the corner of the bathroom or near the wall. This is because the flanges can bend and assume an elbow shape that comfortably fits the position and connects to the drainpipe.

Types of Flanges

Now that you know the different shapes and sizes, there are also various materials that make the flanges. The material is essential since it determines the durability and ease of installation.


Plastic PVC flanges are the most common in the market today and are readily available. They also work well in both residential and commercial buildings. These plastic flanges have the following characteristics:

  • Lightweight
  • Durable
  • Extremely strong
  • Long lasting
  • Affordable
  • Easy to install
  • Waterproof
  • Rust resistant

However, if you have uneven flooring, these PVC plastics may not withstand the pressure and can easily break. In that case, you need to install an ABS plastic flange that is lighter and stronger.


Brass flanges used to be very common, but most people shifted to other options because brass rusts easily when in contact with moisture. However, people still use them because these flanges are strong and come in all shapes and sizes.

Stainless steel

This material is extremely strong and durable. With constant cleaning and maintenance, it can last up to decades. The most recent kind is an alloy of chromium and nickel with a silicon coat to prevent oxidation of the metal.


Copper flanges are rust resistant and very durable. Most people prefer soft copper since it is easy to install and flexible. However, rigid copper fits best in corners and elbow-shaped joints. Another benefit is that it keeps away pests and bacteria, thus creating a hygienic environment in the bathroom.

Cast Iron

This type of flange is tough and custom made to fit the shape of the outlet. It is also moisture-resistant, allowing it to serve you for many years without any sign of rusting. However, the only downside is that these flanges only work for steel piping.


These flanges are almost extinct in the market today. However, people love them because they are durable and lightweight. Currently, you cannot find plain aluminum flanges since most have a combination of zinc, manganese, and copper to make them stronger.

With these details, you can now clearly identify the kind of flange that your toilet requires. Please consult our experts to know what flange best suits your bathroom based on placement and quality. Additionally, we discourage installing it without the help of our professionals since you may loosely fit the flange or use the wrong tools that may damage the system. Our local experts serve the Canton, MA area and will help you inspect and replace the flanges and perform any other required repairs for the bathroom plumbing and the home.

In addition to plumbing, we offer services for dealing with your furnace, air conditioner, and heat pumps. We even work with ductless mini-split systems!

Contact the Green Energy Mechanical Inc experts today, and book an appointment with us for professional plumbing solutions at affordable prices.

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