Free tool

IICRC S500 Equipment Calculator & Cheat Sheet

Room & Water Class

Dimensions (ft)

Optional

Water class

How much water is in the materials? Pick the best fit.

Results

Pints Per Day Required

48

Air Movers Required

6

Square footage300 sq ft
Volume2,400 cu ft
  1. The PPD Formula: Take the room's volume in cubic feet (length x width x height) and divide by 50 for Class 2 water to estimate pints per day required.
  2. The Air Mover Formula: Calculate the square footage of the room (Length x Width) and divide that number by 50.
  3. The Wall Rule: Add 1 additional air mover for every 10 to 15 linear feet of wall space.
  4. The Inset/Offset Rule: Add 1 additional air mover for every inset or offset in the room's architecture that is greater than 18 inches.
Water classes explainedShow

IICRC water classes describe how much water is present and how hard it is to remove—not “how bad the flood is” by itself. Use class with material type and drying strategy.

  • Class 1

    Low porosity, minimal absorption. Water on low-evaporation materials (e.g., tile, sealed concrete, cabinet bases)—little has wicked into structure. Drying is usually faster with fewer specialty steps.

  • Class 2

    Significant water in porous materials. Think carpet and pad, cushion under vinyl, or moisture in gypsum wallboard in the affected area—more evaporation load than Class 1.

  • Class 3

    Greatest evaporation load. Water may have come from above or saturated multiple assemblies (e.g., wet insulation, ceilings, walls, and flooring together). Expect more equipment and longer monitoring.

  • Class 4

    Deeply bound or low-permeance materials. Moisture trapped in hardwood, plaster, concrete, or crawlspaces often needs longer drying, specialty methods, or more aggressive dehumidification than typical Class 2–3 scenarios.