Bathroom Sink Rough-in Height – Ultimate Guide

For most DIYers, it’s frustrating finding the correct bathroom sink plumbing rough-in height. When is the rough-in height too low or high? What are the two different rough-in measurements? Thankfully, it’s much more straightforward than you think. 

The rough-in measurement for bathroom sinks is the distance from the base of the floor to the sink. Most plumbers use a height measurement of 18 to 20 inches for sink drain lines and 20 to 22 inches for the water supply pipe. 

This article will explain the correct dimensions for your bathroom sink drain pipes, water supply pipes, and other essential parts in DIY Plumbing. 

What is the Right Height for a Bathroom Sink’s Rough-in Plumbing?

Your preference determines the rough-in measurement for a bathroom sink. For example, you may set a height compatible with both adult and children users. 

The correct bathroom sink rough-in plumbing height is 18 to 20 inches for drain pipes and 20 to 22 inches for supply pipes. Most importantly, measure from the base floor.

The floor type also dictates the bathroom sink rough-in dimension. So, increase the sink height if you measure from the base floor. However, reduce it by a few inches when measuring from a remodeled or finished floor. 

Also, keep in mind that these dimensions are not compulsory. You may increase or decrease it, depending on the average height of the house inhabitants. Furthermore, know the city’s regulations and guidelines for bathroom sink rough-in dimensions. 

How High Should the Bathroom Sink Be? 

Dear DIYers, the height of your supply and drain pipes is different from the bathroom sink height. Since the sink is placed right on top of these pipes 

The bathroom sink height should be within 29 and 36 inches from the base floor or subfloor. Moreover, most modern plumbing practices choose an average of 36 inches off the ground level. 

The 36-inch height is mostly for bathroom sinks in adult spaces, such as the master bedroom. However, you may use the 32-inch dimension for adult and children-shared areas. 

Factors to Consider When Choosing a Bathroom Sink Height 

As a DIYer, you must consider the following features when choosing the right bathroom sink rough-in plumbing height:

  1. The type of sink 
  2. Placement of existing power outlets
  3. Location of plumbing 
  4. Intended Users 

Type of Sink 

There are about six different types of sinks, each with varying thickness levels and height. You may need to add the sink height to your measurement. You also need to consider the countertop thickness and cabinet height. 

Drop-in sinks can add more than a few inches to your overall measurement. 

On the other hand, you have more flexibility with wall-hung sinks. You can place them at any preferred height. To install wall-hung sinks, attach a holder to the wall and fix it in line with the supply and drain lines. 

Vessel sinks have a deep-bowl-like build, adding to the sink’s overall height. Furthermore, these sinks sit atop the countertop. So, you may include the countertop and cabinet height to the sink’s weight. 

bathroom sink height calculation

Location of Plumbing 

The position of the pipes is essential, especially if you didn’t work on the rough-in plumbing. A too-low drain pipe and supply pipe will limit your chances of fixing a taller bathroom sink. 

The Intended User 

Is it wheelchair accessible or favorable to children? These questions should help shape your decisions when selecting the right bathroom sink size. 

What Are the Full Dimensions for Bathroom Sink Rough-in Plumbing?

Dimensions matter in rough-in plumbing. A wrong measurement is often too expensive or stressful to amend. So, here are the dimensions you need to focus on during rough-in plumbing for bathroom sinks:

The Supply Line (Height)

The vertical supply line is often two to three inches above the drain pipe. You can easily connect a half-inch pipe to the sink from the bathtub, shower, or toilet. So, make two vertical openings about two or three inches above the drain pipe. 

On the other hand, make a hole 4 inches from the left side and four inches from the right side of the bathroom sink center. Two supply lines run horizontally, one for cold water and the other for hot water. 

Discharge Hole 

The drain pipe is a vertical centerline. Furthermore, it must be 16 to 20 inches above the base or sub-floor level. 

Sink Height

Place the sink at an average of 31 inches above floor level. Measure the height, starting from the rim of the bathroom sink. 

Fixture (Side-to-Side Buffer)

The plumbing fixture must be a minimum of 15 to 20 inches from the centerline. 

Fixture (Front Buffer)

Ensure that the gap to the closest obstruction is between 21 to 30 inches. 

You may contact the government body responsible for safe housing guidelines for more information. 

What Are the Dimensions for Rough-in Plumbing for Vanity Cabinets? 

Vanity cabinets enhance the aesthetics of your bathroom. You need to re-adjust your measurement if you plan to install a bathroom vanity cabinet. Vanity cabinets add extra height to the overall height of the bathroom sinks. 

So mark off the drain and supply lines in line with industry standards. 

You may place the supply line at 22 to 24 inches from a finish or subfloor. Put the drain line about 4 inches from the supply line and at a lower height. Note that taller vanity cabinets require longer supply and drain lines. 

Always consult your city’s green building specifications and plumbing codes. You can also contact a building inspector for more information on building regulations and local codes. 


It’s all right to have conflicting views about the bathroom sink’s height in rough-in plumbing. You are in charge of choosing the perfect height for your bathroom sink. Always consider convenience and aesthetics when choosing the right height for bathroom sinks.