How much does it cost to add a bathroom?

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Bathroom Addition Cost Guide

Updated: Jul 29, 2021

Reviewed by Cristina Miguelez remodeling expert. Written by

Adding another bathroom to your home can make life much easier. An additional bathroom provides options to the house’s occupants and can accommodate more residents at once. New bathrooms come in many shapes and sizes, from tiny half baths to large spa-quality master bathrooms. You can add a bathroom to your home by converting an existing space into a bathroom, such as converting an unused bedroom or walk-in closet into a bathroom. Or, you can add a full addition to your home and expand your total square footage while adding a bathroom at the same time. Both these bathroom additions are common, come in many sizes and styles, and have a wide range of costs.

The national average cost to add a bathroom to a home is $15,000 to $40,000, with most people paying around $25,000 for a 48 sq.ft. full-sized bathroom in a new space addition. This project’s low cost is $10,000 for a 48 sq.ft. full-sized bathroom conversion in an existing space with no modifications or new plumbing lines. The high cost is $60,000 for a 100 sq.ft. master bathroom addition in a new space addition.

Cost To Add a Bathroom

Bathroom Addition Cost
National average cost$25,000
Average range$15,000-$40,000

Bathroom Addition Cost per Square Foot

Like many major home projects, your bathroom addition can be loosely calculated by the space’s square footage. Larger spaces cost more to build or convert than smaller spaces. The addition type also impacts cost.

The cost to put in a bathroom varies depending on where the new bathroom is, its size, and whether this is a space conversion or new space addition. The average cost per square foot for converting an existing space is $200 to $250 a sq.ft. The cost to build a new addition that includes a bathroom ranges from $400 to $600 a sq.ft., making existing space conversions more affordable in most cases. Below are some of the most common new bathroom sizes and their average costs.

Cost to Add a 35, 48, 64, 75, or 100 Sq.Ft. Bathroom in an Existing or New Place (mobile)

SizeAverage Cost (in an Existing Space)Average Cost (Build a New Addition)
35 sq.ft.$7,000 - $8,750$14,000 - $21,000
48 sq.ft.$9,600 - $12,000$19,200 - $28,800
64 sq.ft.$12,800 - $16,000$25,600 - $38,400
75 sq.ft.$15,000 - $18,750$30,000 - $45,000
100 sq.ft.$20,000 - $25,000$40,000 - $60,000

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Bathroom Addition Cost by Type of Bathroom

The bathroom type you install dictates some of the costs. For example, adding a small half bathroom costs less than a full bath. Bathrooms come in many shapes, sizes, and configurations, with their use sometimes dictating their size.

Cost of Bathroom Addition in Existing or New Space by Type of Bathroom: Half Bath, Powder Room, 3/4, Small, Full, Guest, Master... (mobile)

Type of BathroomAverage Cost (in an Existing Space)Average Cost (Build a New Addition)
Half Bath$3,000 - $5,000$8,000 - $12,000
Powder Room$3,000 - $5,000$8,000 - $12,000
¾ Bathroom$5,000 - $7,500$10,000 - $18,000
Small$5,000 - $7,500$10,000 - $18,000
Full$7,000 - $12,500$14,000 - $30,000
Mobile Home$7,000 - $12,500$14,000 - $30,000
Guest$7,000 - $12,500$14,000 - $30,000
Wet Room$10,500 - $17,500$15,750 - $32,500
Jack and Jill$14,000 - $22,500$28,000 - $54,000
Master$20,000 - $40,000$40,000 - $96,000
High-End$40,000 - $80,000$80,000 - $192,000

Add a Half Bath

The cost to add a half bath is $3,000 to $5,000 in an existing space. The cost is $8,000 to $12,000 when building a new addition. Half baths are small bathrooms containing a toilet and sink. They average between 15 and 20 sq.ft. They can be added to many spaces because of their size, such as closets. This is considered a micro addition if you build out.

Add a Powder Room

The cost to add a powder room averages $3,000 to $5,000 in an existing space. When building a new addition, expect to pay $8,000 to $12,000. Powder rooms are typically half baths. They measure between 15 and 20 sq.ft. A powder room is usually more formal than a typical half bath. They are most often installed near foyers and other spaces guests might visit.

Add a 3/4 Bathroom

The cost to add a ¾ bathroom ranges from $5,000 to $7,500 in an existing space. If you are building a new addition, the cost averages $10,000 to $18,000. ¾ bathrooms typically contain a sink, toilet, and stall shower but no tub. They usually measure between 25 and 30 sq.ft. These bathrooms are also small enough to often be added to existing spaces without many modifications. They are still considered micro additions if added as a new addition.

Small Bathroom Addition

The cost to add a small bathroom is $5,000 to $7,500 in an existing space. When building a new addition, the cost ranges from $10,000 to $18,000. Small bathrooms are usually 20 to 35 sq.ft. Most ¾ bathrooms are considered small bathrooms. They allow bathing and have room for a small vanity with a sink for storage. Small bathrooms can usually be added to existing spaces fairly easily.

Add a Full Bathroom

The cost to add a full bathroom averages $7,000 to $12,500 in an existing space. The cost is $14,000 to $30,000 when adding a new addition. Full bathrooms start at around 35 sq.ft. with up to 50 sq.ft. also being common. Any bathroom can be considered a full bathroom if it has a sink, toilet, and a full tub and shower. In most cases, the tub and shower are together in an alcove. Larger bathrooms may still be considered full but start to cross into other categories.

Adding a Bathroom to a Mobile Home

The cost to add a bathroom to a mobile home is $7,000 to $12,500 in an existing space. When adding a new addition, expect to pay $14,000 to $30,000. Most mobile homes have bathrooms between 35 and 50 sq.ft. While many mobile homes are not large, some have the space to convert an unused room or area into a second bathroom. You can also add onto the side of a mobile home in a small or micro addition to gain an extra bathroom. Costs are similar to adding a bathroom to a stick-built home.

Add a Guest Bathroom

The cost to add a guest bathroom is $7,000 to $12,500 in an existing space. If you are adding a new addition, the cost ranges from $14,000 to $30,000. Guest bathrooms are normally full bathrooms adjacent to a guest bedroom. They measure between 35 and 50 sq.ft. Guest bathrooms can be easy conversions from existing areas. However, they are more difficult to add on their own and are often new space additions alongside a new guest room addition.

Adding a Wet Room

The cost of a new wet room averages $10,500 to $17,500 for an existing space conversion. If you are adding this room as a new addition, expect to pay $15,750 to $32,500. Wet rooms are ¾ or full bathrooms that are fully waterproofed. This means the shower does not require a door or a curtain. The water can spray anywhere because all surfaces are protected. This can be a good way to add a shower to a smaller room without making it feel closed off. Costs are higher because of the added labor and material needed to waterproof the room.

Adding a Jack and Jill Bathroom

The cost of a Jack and Jill bathroom ranges from $14,000 to $22,500 when adding one to an existing space. The cost of a new addition averages $28,000 to $54,000. A Jack and Jill bath is located between two bedrooms. It normally has two doors - one attached to either bedroom. These baths measure between 70 and 90 sq.ft. This addition is most common as a conversion of a third bedroom sitting between two others or as part of a major addition of one or two other bedrooms with the bathroom. Because of how it is situated, it is difficult to add it as a new space addition alone.

Add a Master Bathroom

The cost to add a master bathroom is between $20,000 and $40,000 for conversion in an existing space. A new addition averages $40,000 to $96,000. Master bathrooms are large bathrooms generally accessible through a master bedroom. They measure between 100 and 160 sq.ft. They often contain double vanities and tubs and showers. These bathrooms are often large enough to customize the space and add amenities like separate toilet rooms or freestanding tubs.

Adding a Luxury Bathroom

The cost to add a luxury bathroom is $40,000 to $80,000 for an existing space conversion. A new space addition ranges from $80,000 to $192,000. Luxury or high-end bathrooms are between 100 and 160 sq.ft. They contain several amenities, including performance showers and jetted tubs, and the materials are luxurious. This includes marble for floors and walls and natural stone or metal sinks and tubs with handmade vanities. If you are hoping to get a true spa feel from your bathroom, a luxury bathroom can be one way to achieve this goal.

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Cost to Add a Bathroom by Location

Costs for a bathroom addition range depending on where the new bathroom is and how it is built. Converting an existing space within your home can cost less than building a new addition. However, not every area in your home has the same build costs.

Adding a bathroom to an unfinished basement costs nearly as much as an addition. Converting an unused bedroom or closet into a bathroom costs less. A finished interior space that is being tiled and has plumbing nearby may have costs similar to a full bathroom remodel, meaning a tear-out to the studs and remodel. However, you have additional costs if you build a new addition, such as a foundation or crawl space extension, framing, and interior and exterior finishing.

In general, the farther the bathroom is from the already finished areas of your home, the higher the costs. Below are some of the most common places to add a bathroom to your home, along with the costs based on the most commonly sized bathroom added to that space.

Cost to Add a Bathroom by Location: Closet Conversion, Under Staircase, Upstairs, Attic, Build an Addition, Garage, Basement... (mobile)

LocationAverage Costs (Labor Included)
Closet Conversion$3,000 - $7,500
Under Staircase$3,000 - $7,500
Upstairs$7,000 - $12,500
Laundry Room Conversion$7,200 - $9,800
Attic$8,000 - $20,000
Bedroom Conversion$14,000 - $40,000
Build an Addition$14,000 - $96,000
Garage$15,000 - $30,000
Basement$20,000 - $30,000

Converting a Closet to a Bathroom

The cost to convert a closet to a bathroom is $3,000 to $7,500. Most closet conversions are done to accommodate half bathrooms or powder rooms. These spaces only need 15 to 20 sq.ft. to be usable, making a closet conversion possible. Larger bathrooms likely need to take space from adjacent rooms, making the project more time-consuming, invasive, and costly. Closet conversions were once very common as plumbing was brought indoors. This can be a very inexpensive conversion because there is no shower, adding only the sink and toilet. The flooring can be left as is or changed.

Bathroom Under a Staircase Addition

The cost to add a bathroom under the stairs averages $3,000 to $7,500. This is another method of adding a half bath or powder room to many homes. While the space beneath the stairs may be larger than 20 sq.ft., it is unlikely the entire space has ceilings high enough to be considered usable. Therefore, this is another common place to add a half bath, which only needs a sink and toilet. The space can be finished with drywall and flooring. Without a shower, the room does not need to be as waterproof, keeping costs down.

Add a Bathroom Upstairs

The cost to add a bathroom to a second floor ranges from $7,000 to $12,500. Second-floor bathroom additions are most commonly full bathroom additions. They are usually created by taking unused space from other areas, such as a small bedroom or oversized closet combined with the end of a hallway. An upstairs bathroom may be added as a guest bedroom by taking part of an oversized bedroom. It may also be added as a family bathroom or a Jack and Jill by converting a small space between two bedrooms into a bathroom. Adding a bathroom upstairs adds function and value.

Convert a Laundry Room to a Bathroom

The cost to convert a laundry room to a bathroom is $7,200 to $9,800. Laundry rooms make fast and easy bathroom conversions. They are already plumbed and often at least partially waterproofed. The most common laundry room size is 36 sq.ft., which is considered a small full-sized bathroom. It can fit a tub/shower comfortably and a toilet and sink in a small vanity. If you have another place to put your washer and dryer and need an extra bathroom, this can be a great conversion to make.

Add a Bathroom in an Attic

The cost to add a bathroom to an attic averages $8,000 to $20,000. Attic conversions have a wide range of costs for several reasons. The first is accessibility: not all attics have full and readily available staircases. Your attic’s height also plays a role because many attic regulations and requirements restrict how much of the attic can be considered usable space. Finally, attics may or may not have plumbing, finished walls, or flooring. All these impact your costs when considering an attic conversion.

Turn a Bedroom Into a Bathroom

The cost to turn a bedroom into a bathroom ranges from $14,000 to $40,000. Bedroom-to-bathroom conversions are common in homes with much more living space than bathrooms. Because a small bedroom is about the same size as a master bathroom, this is the most common conversion type. However, you can convert a bathroom into a Jack and Jill, depending on the location. Bedroom-to-bathroom conversions require a complete tear down to the studs. They may require running plumbing lines to the area, depending on the location, which impacts total costs.

Build a Bathroom Addition

The cost to build a bathroom addition is between $14,000 and $96,000. While you can add an addition for even a half bath, most people adding a full addition for a bathroom do so for a large full or master bathroom. This is because the pouring of the foundation, framing, and other construction makes up a large part of the costs. Doing so for a small space is often considered not worth the ordeal. Bathroom additions make the most sense as part of a larger addition. However, they can be easily added onto a first story, increasing the square footage and function.

Add a Bathroom to a Garage

The cost to add a bathroom to a garage is $15,000 to $30,000. A new bathroom can be a great addition if you plan to finish your garage, use it for purposes other than storage, or add living space. Most garages are not finished and rarely have plumbing. This, combined with the concrete floor, makes this an expensive addition. The area must be finished, and plumbing lines run to the new location. Drains and toilet waste pipes need to be added by jackhammering through the concrete, increasing costs.

Add a Bathroom to a Basement

The cost to add a bathroom to a basement averages $20,000 to $30,000. Basements have similar issues with renovations as garages. The space is not usually ready for plumbing or drains. It is also not often finished at the time the bathroom is added. The basement also requires waterproofing before the other work can begin, raising costs. It is common to add bathrooms to basements, however. If you are finishing the space and adding a bedroom, a bathroom can add a lot of value.

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Bathroom Addition Cost Breakdown

Not every bathroom addition has the same needs or considerations. Converting a space has a different set of costs and parameters than building a new addition. The things you include in the bathroom and the bathroom size and style influence the final costs. In addition, how close existing plumbing is to the new bathroom and how you plan on finishing the space also impact the cost. The following breakdown is the cost to install a new bathroom, assuming an average full-sized bathroom addition in an existing space and new addition. This assumes midrange materials are used, and no serious modifications need to be made. Many of these things may not be necessary, depending on your project. You may forgo planning and drawings in conversion but need them in a new space addition. You may choose to tile your bathroom walls, choose to add a linen tower or a vanity, or use a pair of pedestal sinks. These costs can give you an estimate of what each component may cost.

Cost Breakdown to Add a Bathroom in an Existing or New Place: Planning & Drawing, Plumbing, Electrical, Lighting, Flooring, Painting, Faucets, Toilet...

ProjectAverage Costs (in an Existing Space)Average Costs (Build a New Addition)
Planning & Drawing$800 - $1,20010% - 17% of final costs
Foundation-$6 - $12/sq.ft.
Framing-$9 - $18/sq.ft.
Siding-$3 - $12/sq.ft.
Roofing-$2 - $3/sq.ft.
Plumbing$3 - $5/sq.ft.$3 - $5/sq.ft.
Electrical$3 - $5/sq.ft.$3 - $5/sq.ft.
Lighting$200 - $1,000$200 - $1,000
Wall Tile$6 - $40/sq.ft.$6 - $40/sq.ft.
Flooring$3 - $20/sq.ft.$3 - $20/sq.ft.
Drywall and Backer Board$1 - $3/sq.ft.$1 - $3/sq.ft.
Painting$2 - $6/sq.ft.$2 - $6/sq.ft.
Tub/Shower$3,000 - $7,000$3,000 - $7,000
Faucets$225 - $475$225 - $475
Toilet$350 - $3,500$350 - $3,500
Sinks$300 - $5,500$300 - $5,500
Vanity and Countertop$2,500 - $3,500$2,500 - $3,500
Linen Tower$500 - $2,000$500 - $2,000
Bathroom Mirror$110 - $240$110 - $240
Shelves$25 - $50$25 - $50

Consider many things when remodeling or adding a bathroom. The space size, bathroom type, and layout are important considerations. Bathroom trends can also determine the best look and style of the bathroom. This is particularly helpful when adding a new bathroom to help with your home’s value or resale. By paying attention to trends, you can reach a larger audience of potential buyers.

According to experts, the top trends for 2021 in bathrooms are spa elements, black as an accent color, and multiple tile patterns within the same space.

Cost of Adding a Second Toilet

Adding an additional toilet costs between $1,500 and $4,000, depending on the toilet type. To install a new toilet, a waste pipe must be installed, which may require cutting or drilling into the floor below. The toilet should tie into an existing stack line and must have a cold water line. Adding a toilet costs $150 to $3,000, plus the cost of the plumbing and toilet. This can be a major project, depending on where you install the toilet.

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Cost of Splitting One Bathroom Into Two

The cost of turning one large bathroom into two smaller ones averages $150 to $250 a sq.ft. The space already has plumbing, so while a few new branch lines may be needed, the extent is not nearly as much as a new addition or running plumbing lines. Otherwise, this is treated like two small bathroom remodels. Things are torn out down to the studs, the new plumbing and lights roughed out, and the new walls put up. The two spaces can be finished like two small bathrooms. Costs depend on how large the space is and what fixtures you install.

Adding a Bathroom to an Old House Cost

The cost of adding a bathroom to an older house ranges from $200 to $250 a square foot if converting an existing space. You must consider several things when adding a bathroom to an older home. The first is plumbing and electrical. If these are up to date, the project can proceed like any other. If they are not up to date, you must fix this before adding a new bathroom.

The second consideration is the flooring. Many older homes have settled over the years, and the floors are not level. When adding a tile floor, the substrate must be level, or the tiles could crack. For this reason, it is usually recommended that older homes use mosaic tile floors because these flex with your home and do not crack.

Classic White Bathroom Design With a Large Tub, Shower, Toilet, and Mirror

Cost to Add a Bedroom and Bathroom

The average cost to add a bathroom and bedroom is between $37,000 and $100,000 for the bedroom addition and $15,000 to $40,000 for the bathroom addition. This gives a total range of $52,000 to $140,000. Your costs are impacted by the addition size, location, and finishing materials. Larger high-end additions cost more than modest additions.

Does Adding a Bathroom Add Value?

In most instances, yes, adding another bathroom to your home can add value. Bathroom additions have an average ROI of 54%. This means that whatever you spend on the addition increases your house’s value by roughly 54% of the total cost. This varies by the area and home type. For example, if you have a three or four-bedroom home with one bathroom, adding a second bathroom can make your home much easier to sell and adds more ROI. However, a home that already has two bathrooms with two bedrooms may not get as big of a return.

What Is Worth More, a Bedroom or Bathroom?

If you are wondering whether to add a bedroom or a bathroom to your home from a resale value or wondering if you should keep a bedroom or convert it into a bathroom, there are several things to consider. First, bathroom additions get a slightly higher ROI than bedroom additions. Bedroom additions typically cost more simply because they are larger, so a bedroom addition may add more monetary value while the percentage is slightly higher for a bathroom.

The second thing to consider is the ratio of bedrooms to bathrooms in the house. It is generally recommended you have two bathrooms for every three bedrooms. If you have one bathroom and three bedrooms, adding a bathroom or converting one has more value. However, adding another bedroom to the home has the most value if you have two bedrooms and four bathrooms.

See the range for bathroom and bedroom additions below.

Comparison of the Cost to Add a Bathroom or a Bedroom (mobile)

AdditionAverage Costs (Labor Included)
Bathroom$15,000 - $40,000
Bedroom$37,000 - $100,000

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Enhancement and Improvement Costs

Add an Exhaust Fan in a Bathroom

Bathroom fans reduce the amount of humidity in the bathroom. They are usually required by code and vent outdoors. You likely need to add one to your addition. They cost about $250 to $500 installed.

Radiant Flooring

Radiant heat flooring can make your bathroom floor more comfortable. This is a good choice in a new addition because it means you do not have to extend the rest of your HVAC to the new area. It may be installed as pipes or an electric mat and goes beneath your tile floor. Costs range from $10 to $25 a sq.ft.

Add a Steam Shower

Adding steam to your shower is a great alternative to performance showers or tubs and may provide positive health benefits. Steam showers can be installed in any shower, provided they have a door that seals shut. The cost for a steam shower is $7,000 to $18,000.

Add a Window to a Bathroom

Adding a window to your bathroom can add natural light to the space. It can also add ventilation and make the room seem larger. The average cost to add a new window to a bathroom is $500 to $800.

Additional Considerations and Costs

  • Guidelines. Visit NKBA to get the most up-to-date bathroom size guidelines to ensure you have the necessary space for your fixture placements to pass code. This should be done in the project design phase.
  • Inspection. It is common to find things inside attics, crawlspaces, and basements that you were unaware of, such as mold, asbestos, or water leaks. You may want to check for these issues before you begin to plan for additional work or remediation.
  • Pets. If you have pets, there are some features you may want to consider adding for their benefit, such as a handheld showerhead ($20-$50) or easy-to-clean porcelain tile.
  • Universal Design. Consider using Universal Design in your bathroom to accommodate ADA guidelines and make aging in place easier. Doing so may also open your home up to a broader market at resale time.
  • Permit. You must have a permit to add a bathroom to your home, and it must pass code. Each state has plumbing requirements and codes, so check before you begin to see what may be required by law.
  • Added value. Adding a bathroom to your home can increase its value. It can also improve your home’s function and make it easier for multiple residents to get ready for their day at the same time.
  • Space. Make sure you consider the space’s size when adding a new bathroom. Not every space is large enough to fit everything. While small spaces can often become half baths, full bathrooms need considerably more room to be comfortable.


  • ​How much does it cost to put in a new bathroom?

The average bathroom addition costs around $15,000 to $40,000 for a new bathroom addition. Costs range depending on whether it is a conversion or new addition and the addition size.

  • How much does it cost to add a bathroom to a basement?

Bathroom additions in a basement cost around $20,000 to $30,000, depending on the finishing and location.​ Basements typically have higher remodeling costs than other areas due to the waterproofing needed.

  • How much does it cost to put a bathroom in the garage?

If the garage is attached to the home, it costs between $15,000 and $30,000. Garages are not normally finished spaces, making the costs of adding a new space more costly.

  • Do I need planning permission to add a bathroom?

Yes, you need to pull a permit and have the bathroom inspected. Laws vary by state, so check with local authorities.

  • Can you add a bathroom anywhere in a house?

Technically yes, but you need to run a waste pipe and stackline for each toilet location for best results, limiting your options. ​Ensure you have enough space for the things you want to add.

  • How much does it cost to add a small bathroom?

The cost to add a small bathroom ranges from $5,000 to $18,000, depending on the total size and if you add it as a conversion or a new space addition.

  • How long does it take to build a bathroom?

This varies depending on whether you are converting an interior space or adding new space. Time of year, project size, and materials have an impact. Plan on a minimum of 2 to 4 weeks for the project, but it may take longer for some additions.