Standards-based educational estimate

Air Mover & Dehumidifier Calculator

Answer a few questions and get IICRC-based air mover, dehumidifier, and HEPA counts — plus what they mean for power, noise, and timeline — in about 60 seconds.

Free · No signup · ~60 seconds

What happened

Water source

Time since event

Water extraction status

Start from a real scenario

Click the situation closest to yours. The form fills in realistic numbers and jumps straight to results — you can still edit anything afterwards.

Presets are educational starting points — adjust every field after loading to match your real situation.

Live equipment plan

5–9

Air movers

2

Dehumidifiers

~4–7

Days drying

Containment≈ 500 sq ft · 3 rooms
+5 more at the high end
Air movers (5–9) Dehumidifiers (2) HEPA (1–2) Containment border
50 sq ft 4,000 sq ft

Your full equipment plan

Plan at a glance

5–9

Air movers

2

Dehumidifiers

1–2

HEPA / neg-air

Intensity

High

Containment

Limited containment likely

Inferred class

Class 3

Power draw

30–43 amps @ 115V

Drying window

4–7 days

Confidence

Medium

What the counts imply

Aggressive drying effort

More equipment means faster stabilization but also more disruption — noise, heat, power draw, and access coordination.

How we estimated this

Expand each section to see the assumptions and formulas behind the equipment ranges.

What this means at home

Noise & airflow

5–9 air movers create an obviously active drying environment, not a subtle one.

Power draw

30–43 amps estimated. Multiple circuits likely needed; discuss outlet planning with your provider.

Heat

Dehumidifiers generate heat as a byproduct. Room temperature may rise during drying.

Timeline

Typical drying window: 4–7 days. Varies with materials, humidity, and equipment performance.

Cost range

$2,000–$4,000

Broad range. Actual cost depends on category, equipment days, demolition, and provider pricing.

Power planning

Dehumidifier & Air Mover Amp Draw (Power Planning)

Restoration equipment runs continuously. Spreading it across circuits prevents nuisance breaker trips and keeps drying on schedule.

EquipmentUnitsAmps @ 115 V

Air movers

~2.5 A per mover @ 115 V — continuous load

5–912.5–22.5 A

Dehumidifiers

~7 A per LGR unit — dedicated outlet recommended

214 A

HEPA / negative-air

~3 A per unit; runs continuously until clearance

1–23–6 A
Total estimated load29.5–42.5 A

~4 dedicated 15 A circuits

Plan for roughly 4 dedicated 15 A circuits — NEC caps continuous loads at 80% of a breaker (≈12 A per 15 A circuit), so splitting across multiple circuits prevents nuisance trips and keeps equipment running.

Questions to ask your mitigation provider

  • What category and drying class are you using, and what readings support that?
  • How many air movers and dehumidifiers are being placed, and what size/class are they?
  • What is the target humidity or drying goal, and how often will readings be logged?
  • If containment is recommended, how will negative pressure or filtration be maintained and documented?
  • What daily documentation should I expect (photos, moisture readings, equipment logs)?

Homeowner preparation checklist

  • Identify which circuits serve the affected area — equipment may trip breakers.
  • Plan for noise and restricted access during drying (average 3–5 days).
  • Photograph all affected areas before equipment placement for documentation.
  • Ask for daily moisture readings in writing — this supports insurance documentation.
  • If you smell something musty but do not see mold, mention it to your provider.

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How this calculates

Every count traces back to a published formula or threshold — nothing here is a made-up ratio.

The IICRC formulas behind the counts

Dehumidifier count uses the IICRC initial dehumidification recommendation formula: room cubic footage divided by a published chart factor (which varies by equipment type and drying class) to get total pints-per-day needed, then divided by a reference unit capacity.

Air mover count uses area-based heuristics common in restoration practice: one mover per 300–400 sq ft of floor depending on material, plus adjustments for wet walls, multiple rooms, and cavity spaces.

HEPA/negative air units (when indicated) use a volume × ACH / 60 formula to compute required CFM, with a safety margin for filter loading and ducting losses. ACH baselines reference Minnesota negative pressure guidance (4 ACH standard, 6 ACH aggressive).

Containment thresholds follow EPA mold remediation guidance: limited containment for 10–100 sq ft of mold, full containment for areas exceeding 100 sq ft.

Cost ranges are broad planning estimates from consumer sources and vary widely by category, market, equipment days, and provider.

Sources: IICRC published dehumidification recommendation factors, EPA mold remediation guide, Minnesota negative pressure guidance, CDC flood safety guidance.

Standards & sources (IICRC · EPA · MN guidance)
IICRC S500 EPA MN Neg. Pressure Standards-based, cited formulas
  • Dehumidifier math uses IICRC published chart factors, not made-up ratios.
  • Containment recommendations follow EPA mold remediation guidance thresholds.
  • HEPA sizing uses ACH math referenced in Minnesota negative pressure guidance.
  • Equipment counts are translated into what homeowners actually care about.
  • Pro mode exposes every formula input for contractors and adjusters.
  • The tool says when it does not know enough to be confident.
Assumptions, limits & disclaimers

Equipment counts are educational planning estimates — final deployment depends on field readings, machine sizing, and professional judgment.

  • Standards-based estimate only. Field verification, psychrometrics, and machine-specific capacities determine actual deployment.
  • Category 3 / contaminated losses and larger mold areas usually require more conservative controls than a simple machine count can capture.
  • Cost ranges are broad planning estimates. Actual cost depends on category, equipment days, demolition scope, and provider pricing.
  • Drying goals should be validated with moisture measurements and documented readings.
  • Sources: IICRC published dehumidification recommendation factors, EPA mold remediation guide, Minnesota negative pressure guidance, CDC flood safety guidance.

Common questions

How many air movers do I need for water damage?

A common starting point is one air mover per 300–400 sq ft of affected floor, with additional movers for wet walls, multiple rooms, and cavity spaces like basements or crawl spaces. This tool estimates a range based on your specific situation.

How many dehumidifiers do I need for a 1000 sq ft basement flood?

A 1000 sq ft basement with 8 ft ceilings is about 8000 cubic feet. Using the IICRC Class 2 LGR chart factor of 53, you need roughly 150 pints-per-day of dehumidification — about two standard LGR units. Class 3 drops the factor to 40 and pushes you toward three units. Class 4 (soaked concrete or hardwood) typically needs a desiccant system. The final count depends on ambient humidity, material permeance, and how aggressively you want to close the gap.

Do I need a dehumidifier for water damage?

Almost always, yes. Air movers evaporate moisture from wet surfaces, but dehumidifiers remove that moisture from the air. Without dehumidification, you are just moving wet air around. This tool uses the IICRC initial dehumidification recommendation to estimate how many units are appropriate.

Do I need HEPA air scrubbers for water damage?

Not for most Category 1 clean-water losses. HEPA scrubbers and negative-air machines become important when containment is warranted: visible mold over about 10 sq ft, Category 3 contaminated water, or demolition that would release spores into living space. The tool turns on HEPA sizing only when those containment triggers are present.

When is containment needed?

EPA mold remediation guidance suggests limited containment for 10–100 sq ft of mold and full containment for areas exceeding 100 sq ft. Category 3 (contaminated) water events also typically warrant containment to control the spread of contaminants during demolition.

What is IICRC Class 3 drying?

Class 3 describes the fastest-evaporation scenarios: water has come from above and saturated walls, ceilings, insulation, carpet, sub-floor, and cushion throughout the area. Because there is water on every surface at once, Class 3 requires the most aggressive initial dehumidification in the IICRC chart — lower chart factor, more pints-per-day, more machines.

What is the difference between LGR and conventional dehumidifiers?

A conventional (refrigerant) dehumidifier is effective when the air is warm and already humid. An LGR (low-grain refrigerant) unit uses a pre-cooling heat exchanger so it keeps removing moisture even as the room dries and the dew point drops — which is exactly the condition a serious drying job produces. For tougher or colder jobs, a desiccant dehumidifier removes moisture chemically and can push humidity even lower than LGRs.

What is Category 3 water?

Category 3 refers to grossly contaminated water that may contain harmful agents — sewage backup, river flooding, or water that has been standing long enough to become unsanitary. It requires PPE, containment, and professional controls, not just fans and dehumidifiers.

More equipment questions (7)

How much electricity do restoration air movers and dehumidifiers use?

A typical restoration air mover draws about 2.5 A at 115 V (roughly 290 W). A standard LGR dehumidifier draws about 7 A (roughly 800 W). A HEPA/negative-air scrubber draws about 3 A. A single room with three movers and one dehumidifier is already pulling around 14–16 A — close to the continuous-load ceiling of a single 15 A household circuit. That is why restoration crews usually spread equipment across multiple circuits and sometimes use dedicated extension runs.

How long will dehumidifiers and air movers run in my house?

Typical residential drying is 3–5 days for Class 1–2 losses and 5–10 days for Class 3–4 losses, running 24/7 until moisture readings return to dry standard for the affected materials. The exact duration depends on material type, ambient conditions, containment, and how the initial equipment count matched the evaporation load.

Is 24 hours enough to dry water damage?

Usually no. Twenty-four hours is enough to make visible surfaces feel dry, but structural materials like drywall, carpet pad, insulation, and sub-floor retain bound moisture for days. The EPA 24–48 hour window refers to how fast mold can begin to grow on wet materials — not how fast they actually dry. Professional crews monitor with moisture meters until readings hit a dry standard, not a time-based deadline.

Why does my restoration company want to cut out drywall?

Wet drywall holds moisture for a long time and becomes a mold substrate if left in place. Flood cuts (typically 12–24 inches above the high-water line) remove the saturated portion, expose the wall cavity and insulation, and let air movers dry the framing. For Category 2 and Category 3 losses the cut is usually non-negotiable; for Class 1 clean water caught quickly, drying in place may be possible.

Can mold start within 48 hours?

EPA guidance emphasizes that mold can begin to grow on wet materials within 24–48 hours. This is why rapid drying is critical and why this tool flags events older than 48 hours as elevated risk.

Is this replacing a certified field calculation?

No. This is a planning estimate to help you understand what a serious setup might look like. Actual deployment depends on field readings, psychrometrics, machine-specific capacities, and professional judgment.

Can I export and share this report?

Yes. Every Palm Build tool is designed to produce a polished PDF and an email-friendly summary so you can share it with a spouse, landlord, property manager, insurer, or adjuster.

Related Palm Build services

Water RestorationMold Remediation

Go deeper

Drying equipment, containment, and cost — explained

Want to understand why the dashboard shows what it shows? Here's the educational content behind the numbers, written for homeowners, property managers, and anyone who wants to hold their restoration crew accountable.

Understanding IICRC drying classes

The IICRC S500 standard — the recognised reference for professional water damage restoration — uses four drying classes to describe how much moisture a loss has actually put into a building. Class is not about severity in a colloquial sense; it is a structured label that sets the initial dehumidification target.

Class 1 is the smallest footprint: a minor event on a low-permeance floor where only a limited area has absorbed moisture. Class 2 covers a full room with wet carpet, pad, and wicking up the walls less than two feet. Class 3 — the fastest-evaporation scenario — is where water has come from above and saturated ceilings, walls, and everything below. Class 4 is specialty drying: significant moisture absorbed into low-permeance materials like hardwood, concrete, plaster, or masonry. Class 4 jobs often need desiccant dehumidification or heat-drying systems because standard LGR equipment cannot pull the room down to the low humidity level those materials require.

Your crew should be able to tell you which class they are using, why, and what moisture readings support that call. If you get vague answers, that is a reasonable cue to ask more questions.

Air movers, dehumidifiers, and HEPA — what each does

A successful drying job is never "just fans." Each piece of equipment has a specific job, and leaving one out is a common reason drying projects stall.

Air movers (the short, loud fans that aim down at a wall or up under a lifted carpet) do not remove moisture at all — they accelerate evaporation from wet surfaces into the air. Dehumidifiers are what actually extract that moisture from the air and dump it out as liquid, usually through a condensate hose. Without enough dehumidification, air movers just push humid air around the room and the structure dries very slowly.

HEPA air scrubbers and negative-air machines play a different role: particulate and pressure control. They are not used to dry a room. They come into play when containment is warranted — visible mold beyond about ten square feet, Category 3 contaminated water, or demolition that will release dust or spores into living space. The ACH (air changes per hour) target for the containment, not the square footage of the room, drives how many HEPA units you need.

When containment is actually required

Containment — the heavy plastic barriers, airlocks, and HEPA-filtered negative pressure zones you see on commercial jobs — is not decoration. It is the primary control the EPA recommends for keeping mold spores or contaminated-water particulate out of the rest of the home during demolition.

The EPA Mold Remediation in Schools and Commercial Buildings guide uses three rough thresholds. For less than ten square feet of mold, standard precautions and minor containment are usually adequate. Between ten and one hundred square feet, limited containment is recommended. Above one hundred square feet, full containment with a decontamination chamber is the baseline recommendation. Category 3 water losses also typically warrant containment regardless of mold size, because the demolition itself will aerosolise contaminants.

This tool follows those thresholds. If you see "Full containment likely" in the dashboard, expect your crew to spend a few hours building plastic before any real demolition happens, and expect to stay out of the contained area entirely until clearance testing is done.

What drives water-damage restoration cost

Restoration bills have a surprising amount of variability because the work sits on top of so many moving parts. A rough mental model helps: the total is the sum of mitigation (equipment days and labor), selective demolition (cutting out unsalvageable wet materials), sanitation (cleaning, antimicrobial treatment, possibly containment), and reconstruction (putting the walls, floors, and cabinets back).

Mitigation is measured in equipment-days: a single air mover or dehumidifier running for one day is one equipment-day, and each type has an industry price. Demolition cost tracks directly with how many feet of drywall, how much carpet, and how much insulation have to come out. Contaminated-water losses almost always cost more not because of the water itself but because the demolition scope is bigger and containment is required. Reconstruction — patching drywall, floating a new floor, rebuilding cabinet bases — is the single most variable line item and depends on your market and finishes.

The cost range in this tool is a broad planning estimate drawn from common residential pricing. It should help you ask sharper questions, not lock in a number before your crew has field readings.

What this tool cannot see

A machine count and a containment label are useful, but they are not a field inspection. This tool cannot see the things that often matter most: hidden moisture inside wall cavities, whether your sub-floor is OSB or plywood, whether the HVAC system drew moisture into ducts, or the actual humidity and temperature at your site.

Treat the output as a reality check. Use it to know what a serious response looks like, to ask sharper questions, and to push back calmly when something feels off. Then let the people with moisture meters, thermal cameras, and IICRC training do the work.

Educational content grounded in IICRC S500 & S520 standards, the EPA Mold Remediation Guide, and CDC flood-response guidance. Palm Build Restoration is an IICRC-certified restoration contractor serving Florida, North Carolina, and the surrounding region.