Free tool · Denton, TX
Mold Growth Risk Calculator
This mold growth risk calculator scores how likely mold is to start after water damage in your home, from 0 to 100. It weighs how long materials have been wet, indoor heat and humidity, what got wet, the water source and how you are drying it.
- 6 quick questions
- Built for North Texas heat
- Next steps with every score
Key numbers
- 24 to 48 hours: EPA drying window
- Below 60%: EPA indoor humidity target
- 30 to 50%: ideal humidity
- 72°F or lower: helps the AC pull moisture
A risk score is an estimate, not a mold test.
Check your risk
Calculate your mold risk after water damage
How the mold growth risk calculator scores you
Each answer adds points. Time counts the most, because the EPA says wet materials dried within 24 to 48 hours usually will not grow mold. Humidity and heat come next. The total is converted to a score out of 100.
| Question | Weight | Why it matters |
|---|---|---|
| Hours since materials got wet | Highest (up to 36 points) | Mold needs steady moisture for a day or two to start |
| Indoor humidity | Up to 21 points | Above 60 percent, materials dry slowly and surfaces stay damp |
| Indoor temperature | Up to 18 points | Warm rooms, especially above 85°F with the AC off, speed growth |
| What got wet | Up to 18 points | Insulation, subfloor and wall cavities hold water and feed mold |
| Drying so far | Up to 12 points | Professional dehumidifiers remove water; box fans mostly move it around |
| Water source | Up to 10 points | Gray water and sewage carry nutrients that feed mold |
Scores under 30 are Low, 30 to 54 Moderate, 55 to 77 High, and 78 or more Very high. Once you reach High, the calculator warns that mold can start on wet drywall and carpet within 24 to 48 hours in warm North Texas conditions.
An example
Drywall wet for 24 to 48 hours, a house at 75 to 85°F, humidity at 60 to 70 percent, clean water, and box fans running scores 54, the top of Moderate. If the AC is off and the house climbs above 85°F, the same leak scores 59, which is High. That is why keeping the AC running after a leak matters so much here.
Why mold risk runs high in Denton County
DFW’s normal summer highs are about 95 to 96°F in July and August, with overnight lows near 76°F, and the area averages about 20 days a year at 100°F or more. Gulf moisture keeps the air humid. When a leak happens in summer, or a storm knocks out power and the AC, wet materials sit in close to ideal conditions for mold. Many homes also have air handlers and water heaters in the attic, where heat is extreme. Our guide on how Texas heat increases mold growth explains this in detail.
What to do with your result
- Low or Moderate. You are likely still inside the drying window. Extract water, pull up wet rugs and pad, keep the AC at 72°F or lower, and confirm with a moisture meter that walls and floors are actually dry.
- High. Get professional drying equipment running today. Do not paint over stains or close up wet walls. Our water mitigation crews map moisture and dry to a measured standard.
- Very high, or you already see or smell mold. Stop running fans that blow across moldy areas, and do not run the HVAC if you suspect it is contaminated. See mold removal after water damage.
The EPA says most people can clean mold areas under about 10 sq ft themselves. For larger growth, contained remediation following IICRC S520 is safer. In Texas, TDLR requires a licensed remediator when mold covers 25 contiguous sq ft or more in commercial buildings and residential properties with 10 or more units. Our mold remediation service uses containment, negative air and HEPA air scrubbers.
FAQ
Mold risk calculator questions
Can this calculator tell me if I have mold?
No. It estimates the risk that mold will grow based on conditions. Only a visual inspection, moisture readings, or testing by a licensed mold assessor can confirm mold.
How fast does mold grow after a leak in Texas?
In warm, humid conditions, mold can begin on wet drywall, carpet pad and wood within 24 to 48 hours. Fast drying is the best prevention.
Why does the calculator ask about box fans versus dehumidifiers?
Fans move air but do not remove water from the room. Dehumidifiers pull moisture out, which lowers humidity and dries materials faster. That difference changes your risk.
What humidity should I keep after water damage?
The EPA recommends keeping indoor humidity below 60 percent, ideally 30 to 50 percent. A simple hygrometer tells you where you are.