Are All Bathroom Sink Drain Pipes the Same Size?

There are a variety of reasons why the sink’s drain pipe may experience leaks or damage. If you are unsure of its measurements, it can be a challenging task to replace the pipe.

Hence, it is understandable that you are willing to know the size of your drain pipe.

This guide will tell you all you need to know about drain tube sizes.

What is the size of a bathroom sink drain pipe?

What size are bathroom sink drain pipes?

The drainpipe size depends on the drain hole outlet. It is vital to know that the drain of a sink should be equal in size or smaller than the drain hole.

If the hole has a diameter of 1.5 inches, the sink pipe should also have a diameter of 1.5 inches. These days, you can find drain pipes in several different sizes.

All you have to do is to get the correct measurements.

The standard size of the sink drain pipe is 1.25 inches in diameter. However, this may vary according to the housing codes in your vicinity.

Some locations may recommend 1.5 or 1.65 inches diameter, and they instruct the home plumbing to follow the same numbers.

Remember that the best fitting is only possible if you purchase a drainpipe similar to the drain hole.

How to choose the correct size of bathroom sink drain pipe?

There are several sizes of drain pipes you can install in the bathroom. The choice of a drain pipe depends on two factors:

Adherence to house codes

Better Homes and Gardens sheds light that sink drain sizes should match the housing codes of each state.

As explained above, the communities have regulations to ensure that the plumbing stays effective and safe.

The homeowners must adhere to these codes to safeguard the integrity of their homes. This will significantly contribute when they plan to resell their home.


All of us unanimously agree that changing the drainpipe is an arduous process. You must ensure that you install the correct pipe size to prevent issues like clogging and leakage.

If the size is too small, there are chances of clogging and drainage obstruction.

In contrast, if you choose a bigger drain pipe, you may face leakage and gradual damage to other portions of the bathroom.

The size of PVC pipes installed in bathroom drainage

Best size for bathroom sink drain pipe

PVC pipes are the most common pipes used for bathroom drains.

The PVC pipes are available in different sizes, and you can install them in various holes. Typically, the diameter of the drainpipe has the size of 1.25 inches (mentioned above).

As for those with 1.5 inches, they have four vertically connected units and three units connected horizontally.

You can also find the PVC pipes with 2-inch diameters. This links to a horizontal stack with over six units and a vertical one with over ten units.

The drain pipes are also available in sizes 3 and 4 inches.

How can you measure the bathroom sink drainpipe?

It will help if you measure the drainpipe to purchase the perfect unit.

Following are some steps that will allow you to get accurate measurements of the drainpipe:

Get the tools

You should find the essential tools before you jumpstart the project of measuring and finding a drainpipe.

Some tools to make measuring a breeze for you are:

measuring tape

  • Lubricant
  • Large adjustable wrench
  • Lock pliers
  • Drain in the pipe

Typically, the bathroom sink drain pipe has a U-shaped tube. Thus, the water may stay back even if you are not using the tube.

The key to getting accurate measurements is to drain all water from the line.

Remove existing drain pipe

You can get a precise measurement if you extract the sink drainpipe. Use the wrench to remove the drainpipe from its hole.

Measure the hole

You can use tape to measure the hole outlet. This tells you the pipe diameter, so remember to note all figures when you are doing so.

Measure the length and breadth of the pipe

You can prevent leakage and get your hands on the best installation if you have precise pipe measurements. You can use tape to get all sizes of the pipe.

Besides these, you should also measure the pipe diameter using a ruler to get an accurate value.

Can the sink drain inside the 2 inches pipe?

The sink having 2 inches diameter can drain in the 2 inches pipe. It has vast space and is commonly used in bathrooms with heavy usage.

If the pipe doesn’t fix well, the sink will not drain adequately, and there will be leakage. Use an extender to install the drain outlet and let the sink drain if this happens.


Are all bathroom sink drain pipes the same size?

Even though we have standard measurements of the sink pipes, one must understand that they are not the same every time. Sometimes, the sizes may vary due to practical reasons or state requirements.

The standard size of a bathroom sink drain pipe is 1.25 or 1.65 inches.

What are the various sizes of plumbing pipes?

When it comes to copper pipes, there are imperial and metric sizes. Metric measurements happen from outside the diameter.

The outside diameter is either 10mm, 12mm, 14mm, and so on.

What is the size of the main drain line?

From washing machines to laundry sinks, the diameter of pipes is 2 inches.

As for those in the bathrooms and kitchens, the tube is usually 1.5 inches. And the main sewer pipe leading to the septic tank is 4 inches.

Final Thoughts

Remodeling a bathroom can be a confusing process. Ensure that you have the right plumbing fixtures to proceed with the process.

Bear in mind piping is essential to create a functional and beautiful bathroom. This includes paying attention to choosing the correct drainpipe that fits sink and line alike.

Although the standard size is 1.25 inches, it could go up to 1.65 inches. Also, it would help if you considered the local housing municipality to go ahead.

Similar Posts