Guide To Toilet Flange Sizes and Types

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A toilet flange is one of those bathroom elements that you’d never think of before it started malfunctioning. We all know why — the flange hides under the closet, connecting your toilet to the floor and the sewer line.

But as soon as it starts giving you headaches, you’ll begin researching toilet flange sizes and types. It’s not rocket science, but you have to be careful and pick the flange that fits your toilet.

Toilet flanges come in various types, shapes, and sizes. Let us explain the key differences.

4 Sizes of Toilet Flanges

Perhaps you’d think that all toilet flanges have one standard size, but different manufacturers deliver different products. We recognize four toilet flange dimensions.

Standard 4×3 Flanges

The most common size is the standard 4×3 inch-flange. Its top is four inches wide, while the bottom has only three inches in diameter. The former connects to the toilet, whereas the bottom element fits the outlet drain.

Three-Inch Flanges

The three-inch closet flanges have the same diameter up and down. This makes three-inch flanges easy to install, but only if your plumbing system supports the exact dimensions.

We should also mention four-inch flanges, but they are much rarer and almost out of use. Four-inch flanges demand wider drain pipes, so it’s hard to imagine someone will install them in a modern bathroom.

Push-Tite Flanges

Push-tite flanges are simple to install as you only need to press them to adhere securely to the floor. They feature gaskets that fit inside pipes and are suitable for use with heavy piping.

What makes push-tite flanges even better is their resistance to extreme conditions — you can find products that easily withstand heat, cleaning chemicals, and moisture.

Odd-Sized Flanges

Every flange that doesn’t fit the abovementioned sizes represents an odd-sized flange. For example, there are flanges with unusual diameters such as 3 1/2 inches (bottom) and 7 inches (top).

Each of the odd-sized flanges requires the extension kit to fit into the standard piping system. It’s the only way to adjust the waste outlet and make the toilet functional.

Toilet Flange Shapes

The vast majority of toilet flanges look the same, but there are a couple of exceptions shape-wise. The three shapes are as follows:

Regular Flanges

Regular flanges are round. They suit the round-shaped opening of the drain pipe, which is far the most popular bathroom solution.

Regular flanges extend five inches down the drain, creating a barrier that prevents bad odors and leakages.     

Deep Seal Flanges

Deep seal flanges are also round, but they dive deeper into the outlet pipe. A typical deep seal flange is 12 inches tall, which means it can go further down the waste pipe of your toilet.

Offset Flanges

As the name suggests, an offset toilet flange is somewhat unusual because they need to adjust to the different toilet floor settings. If your toilet has an awkwardly-placed outlet, you probably need the offset flange to seal the drains.

The offset toilet flange isn’t anyone’s primary solution, but it is mandatory for closets with outlets in the corner of the bathroom or near the wall. In this case, offset toilet flanges help you with their elbow shapes and bending abilities. 

6 Types of Toilet Flanges

Toilet flanges are also different in terms of materials. That’s why we can distinguish between six types of toilet flanges.

Type 1: PVC Toilet Flanges

Many closets have plastic toilet flanges because they offer multiple benefits. You can find them is everywhere, from houses to residential buildings and commercial real estate.

First of all, polyvinyl chloride (PVC) flangers are lightweight and very affordable. The second advantage is the durability — they are made to last. Besides that, plastic flanges are easy to install, rust-resistant, and waterproof.

The only drawback is that PVC toilet flanges demand a perfect installation setting. If your bathroom flooring is uneven, the plastic flange can break sooner than usual. That’s because PVC elements can’t withstand huge pressure when not perfectly sealed.

But there is a solution here as you can use an ABS plastic flange. This model is even lighter and stronger. Naturally, it means that ABS flanges are also a costlier option.

Type 2: Brass Toilet Flanges

Brass toilet flanges used to be common in bathrooms, but they aren’t as popular anymore. The reason is simple — brass is prone to oxidization, which occurs when flanges get in touch with moisture and air.

Apart from that, brass flanges are strong and highly durable. They are also malleable, able to withstand heat, and hold weight with ease. You can find them in all shapes and sizes, which gives you a whole range of installation options.

Type 3: Stainless Steel Flanges

Stainless steel flanges are all about strength — they are incredibly durable, so you can expect them to last for years or even decades. Of course, it requires regular maintenance and cleaning in the long run. 

There are many models of stainless steel toilet flanges, but the popular option is number 304. It’s an alloy consisting of chromium (18%) and nickel (8%). You can also find upgraded models with silicon – it protects the flange from oxidization. 

Type 4: Copper Toilet Flanges

Copper items are yet another classic among toilet flanges, thanks to their corrosion resistance and durability. Many homeowners purchase soft copper toilet flanges because they are flexible and easy to install.

On the other hand, rigid copper flanges need an elbow-shaped joint to apply to the toilet outlet. Another benefit of copper is that it fends off fungi, viruses, and bacteria —  a perfect characteristic for your average bathroom element.

Type 5: Aluminum Toilet Flanges

You probably won’t find too many aluminum toilet flanges out there, but they are worth mentioning. Aluminum is a lightweight material, but that’s not the only advantage — other pros include corrosion resistance and durability.

However, manufacturers rarely make toilet flanges of aluminum alone. They often add traces of zinc, copper, and manganese to make the flange stronger and sturdier.

Type 6: Cast Iron Toilet Flanges

Cast iron is an iron alloy with high carbon content and fine crystallization. It can take any shape before hardening, and it makes cast iron flanges tough, wear-resistant, and durable.

Besides that, cast iron toilet flanges are resistant to water, air, and moisture — the flanges will last for years without signs of rust or corrosion. The downside of cast iron toilet flanges is that they fit iron pipes exclusively.

In other words, cast iron flanges probably won’t suit plastic components or any other non-iron elements in your plumbing system.

Signals That You Need to Replace the Toilet Flange

How do you know it’s time to replace the old toilet flange? You’ll notice that the toilet is not working properly, but a few signals indicate that the flange is the main problem.

Toilet Is Leaking at the Base

The first sign of a broken flange is leakage around the base of your toilet. If you spot a puddle on the floor or around the toilet, the flange and its wax ring are not working as they should. It means you need to detach the bowl and replace both parts.

You Have a Loose Toilet

Do you have a wobbly toilet? If yes, the flange and the wax ring are probably the first to blame. 

To test the flange’s sturdiness, push it down slightly with your palm. If the bowl sits firmly on the base, you won’t be able to dislodge it. In case it’s moving freely while you are pushing, the flange is worn out, and you need to replace it.

The Bathroom Smells Awkward

Sometimes you won’t notice any changes in toilet performance, but you will feel an awkward odor in your bathroom. It’s a sign that your toilet flange is damaged and leaking down the drains.

Continuous ventilation and exhaust fans can only help you temporarily, but the only long-term solution is to check the wax ring and the flange. If they don’t work well, you must replace them right away.

You Haven’t Changed It In a Long Time

Who says you have to wait for the problem to occur? Proactive homeowners know they should change the toilet flange before it starts causing problems. If you haven’t changed it in eight to ten years, think about doing it sometime soon.

The Bottom Line

The toilet flange is a vital part of your whole plumbing system — without it, the bowl can’t affix to the floor. Toilet flange types and sizes may vary, but the most popular products are round and 4×3 inches in diameter. 

If you want to replace the old toilet flange, remember to check these features — its dimensions, shape, and type. After that, you can purchase the same part and install it instead of the old item.


How do you know what size toilet flange you need?

The most popular flange size is 4×3 inches. But you can check the size of your old flange and buy a matching product. You’ll probably see the dimensions on the flange – that’s where manufacturers insert information to specify the product.

How to install a new toilet flange? 

Installing a new toilet flange demands some work in a step-by-step manner. Begin by closing the water supply and uninstalling the tank and the fill hose. The second task is to unscrew the bolts and remove the toilet bowl.

After that, you can remove the wax ring and detach the old flange. When you do it, set the new flange and put the wax ring on top of it. Now you can reinstall other elements – the toilet bowl, the tank, and the fill hose.

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