How much does it cost to add a half bathroom?
How much does it cost to add a half bathroom?
$5,000 – $7,500 cost to convert an existing space to a half-bath
$10,000 – $15,000+ cost to build a half-bath home addition
Cost to add a half bathroom
The cost to add a half bathroom in an existing closet or hall space runs $200 to $300 per square foot, or $5,000 to $7,500 for a 25-square-foot powder room with new plumbing, electrical, and interior finishes. Building a half bath addition costs $400 to $600 per square foot due to the additional foundation work, framing, roofing, and exterior finishing.
| Project type | Average cost per square foot | Average total installed cost |
|---|---|---|
| Bathroom conversion (existing space) |
$200 – $300 | $5,000 – $7,500 |
| Bathroom addition (home extension) |
$400 – $600 | $10,000 – $15,000+ |
What is a half-bath?
A half-bath, also called a powder room or guest bathroom, has only a toilet and sink—no shower or tub. These small spaces range from 15 to 32 square feet and serve as extra bathrooms for busy homes. Most half-baths are conversions of existing spaces like closets or under-stair areas, though they can also be added as new construction inside the home or outdoors as pool baths for outdoor entertaining.
Half-bath conversion cost
Converting existing space into a half bathroom costs $200 to $300 per square foot for the labor and materials. Converting closets, unused rooms, or under-stair spaces is most cost-effective because you work within existing structural frameworks. These conversions use existing electrical circuits, established flooring systems, and easier access to plumbing lines, which saves on costs.
Half-bath addition cost
The cost to build a half bathroom ranges from $400 to $550 per square foot, with luxury finishes pushing costs up to $600 per square foot. New additions require extensive groundwork, including foundation work, new framing, roofing extensions, and completely new plumbing and electrical rough-ins with multiple contractors involved in the project.
Cost to install a half bath by location
The location of your new half bath affects the project cost based on plumbing access, structural work, and available space. A closet or under-staircase area costs $3,000 to $10,000 for a compact half bath that maximizes unused spaces. Laundry room conversions range from $5,000 to $12,000, often with more usable space and access to existing plumbing.
| Location | Average cost | Description |
|---|---|---|
| Attic | $12,000 – $30,000 |
|
| Basement | $10,000 – $25,000 |
|
| Closet | $5,000 – $10,000 |
|
| Garage | $8,000 – $25,000 |
|
| Hallway | $5,000 – $15,000 |
|
| Laundry room | $5,000 – $12,000 |
|
| Under staircase | $3,000 – $10,000 |
|
Cost of adding a half bath by size
The cost of a half bath also depends on the size and fixtures. A 3x5 foot layout is the most compact option, ideal for under-stairs or closet installations with room for a toilet and pedestal sink. A 5x5 space meets the minimum size for ADA accessibility. A 4x8 foot layout offers room for a vanity sink and storage.
| Bathroom size | Square feet | Average conversion cost | Average addition cost |
|---|---|---|---|
| 3' x 5' | 15 | $3,000 – $4,500 | $6,000 – $9,000 |
| 3' x 6' | 18 | $3,600 – $5,400 | $7,200 – $10,800 |
| 5' x 5'* | 25 | $5,000 – $7,500 | $10,000 – $15,000 |
| 5' x 6' | 30 | $6,000 – $9,000 | $12,000 – $18,000 |
| 4' x 8' | 32 | $6,400 – $9,600 | $12,800 – $19,200 |
*ADA compliant minimum
Size directly impacts the installation complexity and overall project cost. Smaller spaces are generally less expensive but may be more challenging to work in, while larger layouts require more resources but offer easier installation access. Larger half bathrooms require:
More materials (flooring, drywall, fixtures)
Additional plumbing and electrical work
More labor time for installation
Potentially more structural modifications
Half bathroom cost factors
The cost of a half bathroom depends heavily on the fixtures and finishes you choose, with prices varying significantly based on quality and style. Standard fixtures like basic pedestal sinks, standard toilets, and ceramic tile flooring keep costs at the lower end of the range.
High-end installations include premium features like custom cabinetry, natural stone countertops, designer tile, luxury fixtures, heated floors, and sophisticated lighting systems, pushing costs to the upper range.
| Fixture | Average installation cost |
|---|---|
| Toilet installation cost | $350 – $800 |
| Sink and faucet installation cost | $580 – $2,000 |
| Countertop and vanity installation cost | $400 – $4,000 |
| Flooring | $350 – $2,500 |
| Plumbing | $450 – $1,800 |
| Electrical wiring | $175 – $850+ |
| Light fixtures installation cost | $100 – $300 each |
| Exhaust fan installation cost | $250 – $950 |
| Mirror installation cost | $140 – $430 |
| Medicine cabinet | $150 – $400 |
Besides the room size and fixture choices, several other factors influence the total cost:
Location and space type: Converting existing space, like a closet or under-stair area, costs less than building new additions.
Second-floor access: Second-floor installations cost more due to limited access for plumbing work.
Basement conversions: Basement conversions may require special equipment like macerating toilets or sump pumps, increasing costs.
Plumbing requirements: Proximity to existing plumbing lines and complex installations requiring extensive rerouting significantly affect costs.
Electrical work: New electrical work for lighting, ventilation, and outlets adds to the budget.
Permits and inspections: Local permits and inspections add to the total cost.
Visit our Small bathroom ideas guide for inspiration and ideas for your half bath project.
FAQs about half-bath additions
How big is a half bath?
A half bath or powder room contains a toilet and a small sink, and most often fits in a 15- to 32-square-foot space. If the space includes a shower as well, it is considered a three-quarter bath.
Does a half bath need an exhaust fan?
Yes, most current building codes require exhaust fans in all toilet rooms. Some codes may allow a window that opens as an alternative to mechanical ventilation.
How much does a half bath add to home value?
A half bath can increase your home's value by 2% to 5%, with homeowners recouping as much as 55% to 65% of their investment. The actual value increase depends on the quality of the finishes and local market conditions. For more info, check out our guide on home improvements that add value.
Getting estimates from bathroom installers
Follow these tips to ensure you choose the best bathroom installation contractor near you:
Get at least three to five estimates, as pricing can vary dramatically between contractors.
Ensure estimates cover all aspects, including permits, materials, labor, cleanup, and any potential additional costs for plumbing or electrical complications.
Ask for contact information of recent customers, though respect that not all homeowners may want strangers visiting their homes.
Understand whether you're receiving a rough estimate or a firm proposal, as this affects how binding the pricing will be.
Discuss expected project duration and daily cleanup procedures to avoid surprises during construction.
Use tape to outline fixtures on the floor at full scale to visualize the layout and ensure adequate clearance before finalizing plans.
Confirm the contractor will handle permit applications and has proper licensing for plumbing and electrical work.
Establish how change orders will be priced and approved during the project.
Questions to ask a bathroom installation contractor
Ask contractors these questions to evaluate their experience, process, and reliability:
Are you licensed and insured for plumbing and electrical work?
How many half bath installations have you completed in the past year?
Can you provide references from recent bathroom projects?
What permits will be required, and who handles the applications?
Do you provide a detailed written estimate with material and labor breakdowns?
What's your estimated timeline for a project like mine?
How do you handle unexpected issues like plumbing complications or structural problems?
What warranty do you offer on your work and materials?
Will you be doing the work yourself or using subcontractors?
How do you handle daily cleanup and debris removal?
What happens if the project goes over budget or timeline?
How do you communicate project updates and changes?
Using our proprietary cost database, in-depth research, and collaboration with industry experts, we deliver accurate, up-to-date pricing and insights you can trust, every time.