At Home Mold Test Kits: What Each Type Can and Cannot Show

Why the petri dish always grows something

The cheapest kits are settle plates: a dish of growth medium you open, leave and close. Pro-Lab’s published instructions, for example, say to leave the dish open for 1 hour, then incubate it for 48 hours. The problem is what the air contains. CDC says “there is always some mold around” and that outdoor mold comes indoors on clothing, shoes, bags and pets. The Minnesota health department says a mixture of mold particles normally exists in all occupied buildings.

Shelton and colleagues report on 12,026 US air samples and found the same four groups most common indoors and outdoors in every season and region: Cladosporium, Penicillium, nonsporulating fungi and Aspergillus. Those are the colonies a plate will grow.

Microbiologists treat settle plates as a qualitative tool. A 2022 review by Manibusan and Mainelis in the Journal of Aerosol Science notes that passive samplers have no known air volume and give only an estimate of concentration, that only cells growing on that medium are counted, and that agar dries out, limiting plates to about 4 hours or less. The University of Connecticut EHS fact sheet puts it bluntly: “it would be rare not to get mold growth on the petri dishes!”

Settle plate limit	Why it matters	Source
Spores are everywhere	Growth is expected in any home, so a positive plate cannot separate normal from problem.	CDC, MDH, UConn
No measured air volume	No concentration, so no comparison with outdoors or between rooms.	Manibusan and Mainelis
Culture only	Molds that do not grow on that medium are never seen.	Manibusan and Mainelis
No outdoor control	There is no baseline to read the plate against.	EPA
No accepted standard	No agreed method for running or reading a home plate.	UConn
It grows mold indoors	The dish supplies food, moisture and a surface.	UConn

The five kinds of home mold test

Every mold test for home use falls into one of five types. They measure different things, so the comparison is about the question each can answer, not which brand is best. Lab methods are explained in depth on our mold testing page.

Kit type	Example	What it measures	Cannot tell you	Useful when
Settle plate	Detekt Home, Pro-Lab	Colonies that land and grow on a dish	Concentration, or normal versus problem	Rarely
Tape or swab, lab analysed	MycoTest, Pro-Lab surface method	What a visible stain is, by genus	Air levels, hidden growth	You want a stain identified
Plates plus lab	ImmunoLytics	Genera and colony counts on plates, plus a swab	Concentration; the maker says not building safety	Seeing which genera grew, cautiously
ERMI dust	EnviroBiomics	DNA of 36 molds in settled dust	A validated pass or fail, per EPA	Extra data in a dispute
Lateral flow dust strip	Healthful Home	Whether certain molds exceed the strip’s detection level	Below that level, nothing	Quick screen, read cautiously
Air quality monitor	Airthings	Humidity, temperature, particles and gases	Mold of any kind	Tracking damp conditions

What the makers charge

These are list prices on each maker’s own product page. Lab fees, shipping and taxes change the total, and sale prices come and go.

Product	Listed price	What is included, per the maker
MycoTest household-supplies kit	$35	Prepaid label, chain of custody and AIHA-accredited lab analysis of your own tape or swab
Healthful Home 5-Minute Mold Test	$35.98 sale, $44.95 list	Lateral flow test on household dust; no lab
Detekt Home mold test kit	$39.99	Six-location plate kit, results in about 72 hours, no lab
Pro-Lab mold test kit	$49.95	Plate and surface methods; instructions name a $40 lab fee
ImmunoLytics Quickstart kit	$216	Five plates and one swab with analysis and a consultation
EnviroBiomics ERMI	$240 to $435	Dust DNA panel by turnaround
Airthings Wave Plus	$249.99	Monitor: radon, CO2, VOCs, humidity; no mold sensor
Airthings View Plus	$329.99	Monitor with particle sensor; no mold sensor

Two pricing details matter. According to Pro-Lab’s page, its $40 lab analysis fee is described as both “available” and “included” in different places, so confirm at checkout; paid separately it would make $89.95. Per the Healthful Home shop page, its three-pack works out to $28.66 a test on sale.

What a lab-analysed kit can and cannot tell you

A lab kit is only as good as the lab. MycoTest states that its analysis is by an AIHA-accredited lab to ASTM D7391, with results in 1 to 2 business days of receipt. You can check any such claim yourself in the AIHA LAP EMLAP directory. Public labs also take homeowner samples: the Wisconsin State Laboratory of Hygiene accepts a piece of the material, a tape lift or a swab, and notes that tape lifts can only be examined microscopically.

The makers’ own limits are the honest part. ImmunoLytics says its results do not “locate an exact hidden source, or certify building safety.” Healthful Home, in its FAQ, says a negative result indicates only that the area sampled “does not contain mold levels above a certain detectable level.”

A lab-analysed kit can tell you	It cannot tell you
Whether a stain is mold or dirt	Whether the air is normal
The genus on a sampled surface	Where hidden growth is
Which genera grew on a plate	A concentration, from a plate
That a lab looked, with a report	That the house is safe
A record for your own files	A clearance after cleanup

Air quality monitors measure conditions, not mold

Electronic monitors are sold beside mold kits, but none of the models checked here lists a mold sensor. According to Airthings, the Airthings Wave Plus sells at $249.99 and the View Plus at $329.99; both measure humidity among other things, and Airthings says humidity above 60% encourages mold growth. That matches EPA's Brief Guide to Mold, Moisture and Your Home: keep indoor humidity below 60 percent, ideally 30 to 50 percent.

EPA notes that a humidity meter is a small, inexpensive instrument costing about $10 to $50 at hardware stores. For mold purposes that meter gives the same useful number as a monitor costing about 5 times the top of that range. Our indoor air quality testing page covers the wider measurements.

What EPA, CDC and health departments say about kits

Body	What it says	Plain meaning
EPA	“In most cases, if visible mold growth is present, sampling is unnecessary.”	If you can see it, do not test.
EPA	Sampling “should be conducted by professionals” with specific experience.	EPA does not endorse DIY sampling.
CDC	“CDC does not recommend mold testing.”	Fix the moisture instead.
California Department of Public Health	Kits “are commercially available, but we do not recommend their use.”	A direct no to kits.
Minnesota Department of Health	Testing “is never a substitute for a thorough visual inspection.”	Look before you sample.
University of Connecticut EHS fact sheet	Does “not advocate for the use of mold petri dishes.”	University safety office, same conclusion.
AIHA LAP EMLAP	Accredits labs for air, surface and bulk mold analysis.	The quality marker for any mail-in kit.

No public health body found for this page recommends settle plates. Where they allow testing, it is professional sampling for a defined question.

How to test a house for mold without a kit

The Minnesota Department of Health advises people to investigate on their own first, with two goals: find where mold is growing, and find the moisture source. EPA's Brief Guide to Mold, Moisture and Your Home supplies the checklist:

1. Follow the water. Plumbing leaks, roof and window leaks, and anything that got wet and was not dried within 24 to 48 hours, which is EPA’s window for preventing growth.
2. Look for condensation. EPA names windows, walls and pipes; rust on a drainpipe is one of its examples.
3. Use your nose. A musty odor in a basement is covered on our musty smell in basement page.
4. Measure humidity. A hygrometer, against EPA’s 60 percent ceiling.
5. Identify a stain only if it matters. A single lab-analysed tape lift answers that; our black mold versus regular mold page covers appearance.

Should you buy a kit, call an assessor, or fix the moisture?

Your situation	Next step	Why
Visible growth under about 10 sq ft	Fix the moisture and clean it	EPA says you can usually handle it yourself; see DIY mold remediation.
Visible growth over 10 sq ft, or lots of water damage	Call a professional	EPA points to its professional guidance; some states license this work (state rules).
Musty odor, nothing visible	Look first, then an assessor	Hidden growth has to be found, not just detected.
A stain you cannot identify	One lab-analysed tape or swab	Cheapest real answer to a narrow question.
Recent leak, nothing visible yet	Dry it within 48 hours	EPA’s prevention window; a hygrometer helps.
Sale, lease dispute or claim	Independent assessor	A kit lacks an independent sampler and outdoor controls; see inspection cost.
Wanting reassurance the house is “safe”	No test	MDH says it is unknown what level of mold is safe.

In one line: if you can see it or smell it, skip the kit; if you need to know what a stain is, mail one tape lift to an accredited lab; if money, a sale or a dispute depends on the answer, hire an assessor who is not the remediator.

For contractors: when a customer hands you a kit result

A customer may call with a plate full of colonies. The useful response is to treat it as a reason to inspect, not as a scope of work, and to write down moisture readings, photos and affected area, because those drive the estimate.

Customer brings	What it shows	What to do
Settle plate with growth	Spores were in the air, as in any home	Inspect and measure moisture; do not scope from it.
Lab tape or swab report	What one stain is	Useful context; still find the moisture and extent.
Lateral flow positive	Dust crossed a strip’s detection level	Inspect; the maker says a negative is not a clearance either.
ERMI score	Dust DNA against a research scale	EPA does not recommend routine use; do not price from it.
High humidity from a monitor	Damp conditions	Find the source; the fix may sit with an HVAC trade.

Where the job needs an assessor, licensing states such as Texas and New York bar one licensee from both assessing and remediating the same project, so refer out. More on the mold hub.

Questions people actually ask

Can I test for mold in my home myself?

Yes, but EPA says sampling should be done by experienced professionals, and California’s health department does not recommend kits. If you want one answer, mail a tape lift or swab of a visible stain to an AIHA-accredited lab; MycoTest lists $35, according to its product page. Skip settle plates, which grow mold in almost any home.

Are at-home mold tests accurate?

It depends on the type. A lab-analysed tape lift can accurately identify what is on a surface. A settle plate cannot be accurate about a mold problem because spores are present in all indoor air and the plate has no measured air volume. Monitors measure humidity, not mold. None can certify a house as safe.

How do I test my house for mold without a kit?

Follow the water and the smell. EPA says to check for leaks, condensation on windows, walls and pipes, and anything wet that was not dried within 24 to 48 hours. A $10 to $50 hygrometer, the range EPA reports, shows whether humidity sits above its 60 percent ceiling. Minnesota’s health department says visual inspection beats testing as a first step.

Do 5-minute mold tests work?

The Healthful Home 5-Minute Mold Test is a lateral flow strip run on household dust that, per the maker, screens for specific mold types above a detection level. Its own FAQ says a negative result means only that levels are below that level, and that confirming indoor air quality needs a professional inspector.

How do I test for asbestos in home insulation?

Do not sample it yourself. EPA says taking samples yourself is not recommended, and its vermiculite guidance says to assume vermiculite insulation may contain asbestos and leave it undisturbed, because testing may be expensive and give erroneous results. Hire an accredited asbestos professional; our asbestos testing kit page explains the options.

Where can I find a reliable asbestos test kit?

Reliability comes from the lab. NIST’s NVLAP programme accredits labs for asbestos analysis by polarized light microscopy and electron microscopy, and federal AHERA rules require NVLAP labs for school samples. Choose a kit that names an NVLAP-accredited lab, and read EPA’s advice against sampling yourself before cutting into anything.

How do I safely dispose of biohazard waste at home?

For used needles, FDA says to place them in a sharps disposal container immediately and dispose of the container according to your community guidelines, which vary by location. Blood or body-fluid contamination after an incident is a different job; see our biohazard cleanup page.