Enter your job details below to get equipment recommendations based on IICRC S500 guidelines. This calculator helps restoration contractors properly size dehumidifiers, air movers, and air scrubbers for residential and commercial water damage projects.
Disclaimer: These recommendations are estimates based on IICRC S500 guidelines. Actual equipment needs may vary based on specific job conditions, moisture readings, and environmental factors. Always verify with moisture meters and adjust accordingly. For critical projects, consult with a certified restoration professional.
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How the Equipment Counts Are Calculated
Water damage equipment calculator estimates use the IICRC S500 initial sizing chart. For refrigerants, divide cubic feet by the refrigerant chart factor to get required pints/day. For desiccants, multiply cubic feet by the desiccant air-change rate and divide by 60 to get required CFM. Each card's unit count uses that machine's own AHAM rating for refrigerants or CFM rating for desiccants, rounded up.
The calculator maps Light to Class 1, Moderate to Class 2, and Severe or Category 3 to Class 3. Hardwood or concrete with damage above Light maps to Class 4. Category describes contamination; class describes the evaporation load used for sizing.
Air movers are estimated at one per 100–150 sq ft of wet floor or one per 10–16 linear ft of wet wall. Air scrubbers are counted only for containment, mold, sewage or Category 3 water.
These are starting counts, not gospel. Moisture readings on day two tell you whether to pull equipment or add it. That's also why the disclaimer above matters: a calculator can't see your moisture map.
Frequently Asked Questions
How many air movers do I need per dehumidifier?
The working ratio is 4 air movers per dehumidifier. Air movers push moisture off wet surfaces into the air; the dehumidifier pulls it out. Run too many air movers without enough dehumidification and you just move humid air in circles — the structure stays wet.
How many dehumidifiers per square foot of water damage?
The water damage equipment calculator sizes refrigerant dehumidifiers using cubic feet, water-damage class and each unit's AHAM rating. Square feet alone aren't enough.
For example, 1,000 sq ft × 8 ft = 8,000 cu ft. For Class 2 with LGR units, 8,000 ÷ 50 = 160 pints/day required. That calls for two 147-pint/day units because one falls short. Use AHAM ratings measured at 80°F and 60% RH, not saturation ratings measured at 90°F and 90% RH. Shop dehumidifiers for water damage restoration.
What is the difference between Category 1, 2, and 3 water?
Category 1 is clean water from a supply line or rain. Category 2 ("grey water") carries contamination — washing machine discharge, toilet overflow with urine. Category 3 ("black water") is grossly contaminated: sewage, flooding from rivers, anything that sat for 48+ hours. Category 3 requires containment, HEPA air filtration, and disposal of porous materials. For extraction gear on Category 3 losses, see flood and water extraction equipment.
When do I need air scrubbers on a water damage job?
Any time contamination is airborne or about to be: Category 3 water, visible mold, or demolition inside an occupied building. For standard clean-water drying, you usually don't need them. The calculator adds scrubbers automatically when you select Category 3 or mark containment as required.
Can I use a residential dehumidifier for restoration work?
It will pull some water, but a 50-pint home unit extracts a fraction of what an LGR does at restoration conditions and has no condensate pump, no hour meter, and no stacking frame. On a billable job, drying time is money — a $250 home unit that doubles the dry-out costs more than it saves.
What happens to drying equipment below 60°F?
Standard refrigerant dehumidifiers lose extraction fast below 60°F and can ice up entirely. Either heat the space to 70–80°F or switch to desiccant dehumidifiers, which keep working in cold conditions. The calculator switches its recommendation to desiccant when you select a cold environment. See our desiccant dehumidifiers.
Browse water damage restoration equipment — LGR dehumidifiers, air movers, and air scrubbers with prices listed. No quote required. Sizing a specific dehumidifier? Use the dehumidifier sizing calculator.