Mold remediation cost calculator

Enter the moldy area and where it is. Add HVAC or duct work, testing and drywall replacement. See the low, typical and high price for your state, with the guides' range for that part of the house as a check.

$17.50Typical per sq ft of mold

$500 to $1,000A small job, like a bathroom

10 sq ftEPA's do-it-yourself limit

Mold remediation cost

$1,000 to $2,500

Typical $1,750 (US average)

$1,000Low

$2,500High

Fix the moisture first: the leak, the humidity or the drainage. Without that, mold comes back. The EPA advises professional help for areas over about 10 sq ft or after significant water damage.

Free. Your numbers become an estimate you can send from your phone.

How we got this

Remediation100 sq ft × $10 to $25 a sq ft (typical $18) = $1,000 / $1,750 / $2,500This Old House, HomeAdvisor and Bob Vila give $10 to $25 a sq ft, Fixr $10 to $30. Middle of the lows, highs and midpoints. Covers containment, air scrubbing, removing or cleaning moldy material, and treatment.
Basement cross-check$500 to $3,000HomeAdvisor, This Old House and Bob Vila's whole-job range for mold in this location.
RegionUS average prices (no ZIP entered)Enter a ZIP to scale the labor part of the price to your state's wages.
Total$1,000 to $2,500, typical $1,750

Item	Qty	Low	Typical	High
Mold remediation, basement	100 sq ft	$1,000	$1,750	$2,500
Total		$1,000	$1,750	$2,500

Sources: This Old House, mold remediation cost; HomeAdvisor, mold remediation cost; Bob Vila, mold remediation cost; Fixr, mold remediation cost; EPA, a brief guide to mold, moisture and your home; BLS Occupational Employment and Wage Statistics, May 2025 (state and national files); US Census Bureau, 2020 ZIP Code Tabulation Area to county relationship file. Checked 2026-10-08.

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Key takeaways

Professional mold remediation usually costs $10 to $25 a square foot of affected area, about $17.50 typical.
Small jobs cost $500 to $1,000; whole-house jobs after a flood run $10,000 to $30,000.
Mold in the HVAC system costs $3,000 to $10,000 to treat. Testing runs $250 to $800.
Fix the moisture first. Remediation without fixing the leak or the humidity is money spent twice.

How much does mold remediation cost per square foot

Mold remediation companies price by the size of the affected area, then adjust for where it is and how deep it goes. This Old House, HomeAdvisor and Bob Vila all put it at $10 to $25 a square foot. Fixr's size table works out to $10 to $30. The middle of those is $10 to $25, with $17.50 typical.

Moldy area	Low	Typical	High
50 sq ft	$500	$875	$1,250
100 sq ft	$1,000	$1,750	$2,500
200 sq ft	$2,000	$3,500	$5,000
500 sq ft	$5,000	$8,750	$12,500
1,000 sq ft	$10,000	$17,500	$25,000

As whole jobs, HomeAdvisor's average is $2,368 and Fixr's is $3,500 for an attic, with most between $1,500 and $9,000. This Old House puts a small infestation at $500 to $1,500 and whole-house work at $10,000 to $30,000.

What pushes a job toward the top of the range:

Depth. Mold on the surface of tile or sealed wood cleans off. Mold in drywall, insulation, carpet pad or ceiling tiles means cutting it out and bagging it.
Access. A tight crawl space or a low attic slows the crew, and each bag has to be carried out through the house.
Containment. Large or heavily contaminated areas need sealed plastic rooms, negative air machines and more time on site.
Water damage behind it. If the subfloor, framing or sheathing is rotten, carpentry gets added to the job.
Rebuild. Remediation companies often stop at removal and cleaning. Putting back drywall, insulation, flooring and paint can be a second bill from a second contractor.

The square footage is the surface with mold on it, not the floor area of the room it is in. Measure the patches you can see, then expect the crew to find more once they open a wall or lift a floor.

Mold removal cost by location

HomeAdvisor, This Old House and Bob Vila print the same whole-job ranges by where the mold is. Fixr's are close.

Location	HomeAdvisor, This Old House, Bob Vila	Fixr
Bathroom	$500 to $1,000	$500 to $1,500
Crawl space	$500 to $2,000	$500 to $2,000
Basement	$500 to $3,000	$1,500 to $4,000
Attic	$1,000 to $4,000	$1,500 to $9,000
Inside walls	$1,000 to $20,000 (HomeAdvisor)	$1,000 to $12,000
HVAC system	$3,000 to $10,000	$3,000 to $10,000
Whole house	$10,000 to $30,000	$10,000 to $30,000

Bathrooms are usually surface mold on tile, grout and caulk. Behind the tub or shower wall is a different, bigger job.
Basements and crawl spaces grow mold from damp air and seepage. Bob Vila notes the price is on top of any waterproofing needed to stop it.
Attics grow mold from roof leaks and bathroom fans or dryer vents dumping moist air into them. Bob Vila says long-running attic mold can reach $7,000, plus the roof repair.
Walls are the wide range because drywall is porous. Surface mold can be cleaned; mold that grew through from behind means cutting out the board.
HVAC spreads spores through the house. Bob Vila puts furnaces and air handlers at about $3,000 to $5,000 and air conditioning systems up to $10,000.

Mold testing, and does the type matter

HomeAdvisor puts basic mold testing at $250 to $350 and testing with lab analysis at $450 to $800. You do not always need a test. If you can see and smell it, it is mold, and it needs removing whatever kind it is. Testing earns its cost when you suspect hidden mold, when someone in the house has health problems, for a real estate sale, and after remediation, to show the work is done.

Bob Vila lists remediation costs by mold type:

Mold	Average remediation (Bob Vila)
Chaetomium	$600 to $5,000
Ulocladium	$600 to $6,000
Alternaria, Aspergillus, Cladosporium	$700 to $6,000
Black (Stachybotrys)	$800 to $7,000
Serpula lacrymans (dry rot)	$800 to $7,000
Fusarium	$800 to $8,000

The ranges overlap almost completely, which tells you the size and location of the growth matter far more than the species. Black mold costs a little more mostly because crews take extra containment and protective steps. The method is the same for every type: contain the area, remove what cannot be cleaned, clean what can, dry everything, and fix the moisture.

HealthMold can trigger allergies and asthma and irritate eyes, skin and lungs. Keep children, older people and anyone with breathing problems away from the work area. Professionals seal the space with plastic and run air scrubbers under negative pressure so spores do not spread through the house.

A worked example: a damp basement wall

After a wet spring, a finished basement has mold on about 100 sq ft of the lower drywall along one wall, and a musty smell. The owner wants a basic test to see whether it has spread.

Remediation. 100 sq ft × $10 / $17.50 / $25 = $1,000 / $1,750 / $2,500.
Basic test. $250 / $300 / $350.
Total. $1,250 to $2,850, with $2,050 typical at the US average.

The basement range of $500 to $3,000 in HomeAdvisor, This Old House and Bob Vila brackets it. If the drywall has to come out and be replaced, add HomeAdvisor's $1,000 to $2,900.

A second example: a 200 sq ft patch of mold on the roof sheathing in an attic, traced to a bath fan venting into the attic, with mold also found in the air handler. Remediation is 200 × $10 / $17.50 / $25 = $2,000 / $3,500 / $5,000, the HVAC system adds $3,000 / $6,500 / $10,000, and a test with lab analysis adds $450 / $625 / $800. That is $5,450 to $15,800, about $10,625 typical, before rerouting the fan outside, which is a small job by comparison and the one that keeps the mold from coming back. Fixing the water coming in is a separate cost; see our basement waterproofing cost calculator and French drain cost calculator. Enter a ZIP to scale the labor share to your state.

Clean it yourself or hire a remediation company

The EPA's guidance draws the line at about 10 square feet, roughly a 3 ft by 3 ft patch. Smaller than that, most people can clean it themselves once the moisture problem is fixed, wearing an N-95 respirator, gloves and goggles. HomeAdvisor puts the gear and cleaners for a job that size at $50 to $300.

Bigger than that, after a lot of water damage, in the HVAC system, or if anyone in the house is sensitive, the EPA points people to professional remediation. Ask any company:

How they will contain the area and protect the rest of the house.
What they will remove and what they will clean.
Whether they found and will address the moisture source, or who will.
Whether the price includes a clearance test afterward, and who does it. An independent tester avoids a company grading its own work.
Whether their workers are trained in mold remediation, and whether they carry liability insurance that covers it. Many general policies exclude mold.
What happens to drywall, insulation, carpet and trim they remove, and whether putting them back is included.

Stopping mold from coming back

Mold needs moisture. Take that away and it cannot grow. The EPA puts it simply: the key to mold control is moisture control. Fix leaks fast and dry water-damaged materials within 24 to 48 hours.

Humidity. The EPA says to keep indoor humidity below 60%, ideally 30% to 50%. A dehumidifier in a basement or crawl space does most of the work, and a cheap humidity meter tells you if it is enough.
Ventilation. Run bathroom fans during and after showers, and make sure bath fans and dryer vents go outside, not into the attic. Our dryer vent cleaning cost calculator covers that job.
Water outside. Clean gutters, run downspouts away from the house and slope soil away from the foundation.
Leaks. Bob Vila puts fixing small leaks around the home at about $150, far less than any remediation job.

The EPA also flags condensation as an early warning: water collecting on windows, walls or pipes is a sign the air is too humid. Dry the surface and deal with the source. Vent clothes dryers, stoves and bath fans outside, and run a fan or open a window when cooking, showering or washing.

How remediation contractors should price a job

Measure the affected area and price by the square foot, with a minimum for small jobs.
Price containment and equipment. Plastic barriers, negative air machines, HEPA vacuums and dehumidifiers by the day.
Separate removal from rebuild. Tear-out, cleaning and treatment on one set of lines; new drywall, insulation and paint on another, or by another trade.
Offer clearance testing by an independent tester as a line the customer can accept.
Mind the margin. Our profit margin calculator shows the price that keeps it.

The "Save as an estimate" button above turns the result into lines. Send it from Koira and the customer can approve it and pay a deposit on their phone.

Last checked October 8, 2026. More for your trade: how trades run on Koira.

FAQ

How much does mold remediation cost per square foot?

About $10 to $25 a square foot of affected area, $17.50 typical. This Old House, HomeAdvisor and Bob Vila all give $10 to $25; Fixr goes up to $30.

How much does it cost to remove mold from a basement?

Usually $500 to $3,000 according to HomeAdvisor, This Old House and Bob Vila, or $1,500 to $4,000 according to Fixr, before waterproofing.

How much does black mold removal cost?

Bob Vila puts black mold remediation at $800 to $7,000, a little more than other molds because of the extra containment.

How much does mold testing cost?

HomeAdvisor puts basic testing at $250 to $350 and testing with lab analysis at $450 to $800.

Can I remove mold myself?

The EPA says patches under about 10 square feet can usually be cleaned by the homeowner with protection, once the moisture is fixed. Larger areas call for a professional.

Does homeowners insurance cover mold removal?

Sometimes. Bob Vila notes mold from an unrepaired leak or unremediated water damage will not be covered, and flood-related mold may need flood insurance. Call your insurer before work starts.

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