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Calcimator

Mold Risk Calculator

Assess mold growth risk from humidity, temperature, surface type, and ventilation quality with dew point analysis.

Inputs

%

Results

Mold Risk Level (1–5)

2

Dew Point (°F)57.4
Critical RH Threshold (%)65
RH Above Threshold (%)0
Est. Mold Onset (days)0
How to Use This Calculator
  1. Enter Relative Humidity (%), Temperature (°F), and Surface Type.
  2. Set Ventilation Quality.
  3. Review the Mold Risk Level (1–5) result.
  4. Use Dew Point (°F) and Critical RH Threshold (%) to inform your decision.

What each input means

Relative Humidity (%)
Current indoor relative humidity. Mold risk increases above 60%.
Temperature (°F)
Indoor air temperature. Mold grows best between 70–90°F.
Surface Type
1 = Organic (wood/drywall), 2 = Semi-porous (concrete), 3 = Non-porous (metal/glass).
Ventilation Quality
1 = Poor (none), 2 = Fair (some natural), 3 = Good (mechanical), 4 = Excellent (dehumidification).

What each result means

Mold Risk Level (1–5)
1 = Low, 2 = Low-Moderate, 3 = Moderate, 4 = High, 5 = Very High.
Dew Point (°F)
Temperature at which moisture condenses. Surfaces below dew point will have condensation.
Critical RH Threshold (%)
Minimum relative humidity for mold growth on the selected surface type.
RH Above Threshold (%)
How far current humidity exceeds the mold growth threshold. 0 means safe.
Est. Mold Onset (days)
Approximate days until mold growth begins at current conditions. 0 = conditions unfavorable.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Relative Humidity (%) = 60, Temperature (°F) = 72, Surface Type = 1, Ventilation Quality = 2 = 4 input(s) provided
  2. Calculate Mold Risk Level
    Mold Risk Level
    2 = 2
  3. Calculate Dew Point
    Dew Point = dewPointC * 9 / 5 + 32
    57.4 = 57.4
  4. Calculate Critical RH Threshold
    65 = 65

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