# How To Measure A Bathtub Drain? (Explanation Inside!)

A standard modern bathtub drain is 1 1/2 inches in diameter, which is the width straight across the middle. For a 1 1/2-inch drain, rough-in plumbing should be calculated. If you are unsure of the diameter of your drain, you can measure it with a tape measure or a ruler. The first step is to determine how deep your tub drain will be.

You can determine the depth of a drain by measuring the distance from one end of it to the other. For example, if you have a 3-foot-long drain and you want to know how much water it will take to fill the tub, measure the length from the end closest to you to that end furthest away from you.

Then divide that number by 3 to get the amount of water that will fit in the drain hole. This number is called the “depth of drain” or “drainage depth.” If the number you get is less than or equal to this number, then you don’t need to worry about it. However, it is always a good idea to double-check your measurements to make sure they are accurate.

There’s even a video explaining it all!

## What are the rough in measurements for a bathtub drain?

You’ll rough in the tub drain with 1 1/2 inch pipe with male threads that extend above the level of the floor. Specific requirements for the trap, drain line, and vent will be discussed later in this chapter. You will rough-out the drain lines with a 1-1/4-in. pipe that extends 3/8 in. above floor level.

This pipe must also be ventilated to prevent condensation from forming on the pipe. If you are installing a new drain, you will need to replace the old drain pipe and install the new pipe in its place. For more information on venting, see Chapter 11, Venting the Bathroom.

## How do you measure a bathroom drain?

To measure the sink drain hole, use the measuring tape. The diameter of the drain pipe is determined by you. Measure the bottom end of the drain using a ruler. This will give you the length of pipe you will need to cut.

If you want to make a longer pipe, cut it in half and then cut the other half to length. Make sure that you cut all the way around the outside of your sink, not just the inside. The pipe will be too long to fit through the hole you drilled in the wall.

If you don’t have access to a drill press, you can also use a hand drill. Drill a hole about 1/4 inch deep and about 3/8 inch in diameter. Be sure to use the right bit for the job. It is a good idea to have a friend or family member help you with this step.

## Are all tub drains in the same place?

The bathtub assembly and drain stoppers are not the same. The type of tub you have is one of the factors that can affect the right drain. The size and shape of the tub and how much water is in it. For example, a large tub will have a larger drain hole than a small tub.

A smaller tub may not have enough room for the drain to be large enough to allow the water to drain out. If you don’t know the exact size of your tub, you can measure it with a tape measure or by looking at it from the side.

You can also look at the dimensions of other tubs in your area to get an idea of what size drain you need. If you are installing a new drain, be sure to check with the manufacturer to make sure it is compatible with your existing drain.

Some manufacturers will not install a drain if the existing one is not compatible, so you may need to purchase a replacement drain from a different manufacturer.

## How much slope should a tub drain have?

The ideal slope for a drain line is 14 inch per foot. For every foot the pipe travels, it should be dropping 14 of an inch of water. If you have a large pipe, you may want to consider using a “slope gauge” to determine how much water you need to drop. This is a simple device that you can buy at any hardware store.

It measures the distance between two points on a pipe and tells you how many inches the line needs to travel to reach that point.

For example, if your pipe is 12 inches long, the gauge would tell you that if you were to run a 12-inch pipe from point A to point B at a rate of 1 foot per second, then you would need a 1-foot-per-second drop in the water level.

If you are running a smaller pipe (, 3 feet long), you could use a gauge that would give you the same information, but it would be a little more complicated to use.

## Are tub drains standard?

The standard tub has a 1.5 inch drain. The attached drain plug makes it easy for the drains to fit. If the drain is too small, you may need to use a larger tub. This is especially true if you are using a tub that has a built-in drain, such as a bath tub or shower.

You may also want to consider the size of the tub and the amount of water that will be in it. For example, if your tub is only 1 1/2 feet long, then you will need a drain that is at least 2 feet in length.

## Can you replace drain in tub?

Regardless of the type of bathtub you own, bathtub drain removal and replacement can be done easily. You can replace the bathtub drain with a different style if you know how to remove the tub drain.

## What is the typical shower drain size?

The majority of shower drainpipes are two inches in diameter, but if you have two-inch drain and you run into a three-inch drainpipe, you’ll be making another trip to the plumbing supply store. O’Brian to always check with local codes. First, make sure the drain pipe is at least three inches long.

If it’s longer than that, it may be a good idea to replace it with a longer one. Third, look at the size and shape of your drain pipes. You may find that they’re too long or too short, and that you need to cut them down to a shorter length.

Finally, if your drains are too small, they may not be able to handle the amount of water that’s going to flow through them. This is especially true if the water is coming from a faucet or a shower head, or if it comes from the toilet or bathtub.

## How do you measure for a drain cover?

To measure the clear opening size for your cover, you need to take the measurements from the inside walls of the manhole from one side to the other. If the hole is square or rectangular, you will need to take both the width and height measurements.

## Can a shower drain be 1 1 2 inches?

For more than 20 years, many plumbing codes have listed the minimum shower drain as 1 1/2 in. The showerhead flow rate was lowered to 2.5 gal. per min. A 1 1/2-in.-diameter drain is too large to fit in a standard shower head.

In the early 1970s, the U.S. Army Corps of Engineers (USACE) began a study to determine the maximum size of shower heads that could be installed in the United States. The results of this study were published in 1975. According to the USACE study, showerheads with a maximum diameter of 1 3/4 in., and a minimum height of 3 in.-high, could not be used for showering in military installations.

In addition, it was determined that a 2-ft.-wide drain was too small to accommodate a shower with this diameter. It was decided to use a drain that was 3 ft. wide at the top, and 2 ft.-long at its base, to allow for the installation of a 3-gallon shower tank. However, this design was not accepted by the military and was never used in any military installation.