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Laundry Room Ventilation Calculator

Size laundry room ventilation in CFM to control the humidity that washers and dryers add.

Measurement units

Bathrooms are often planned around 8 ACH as a rule of thumb.

Free, runs entirely in your browser, and your numbers never leave your device. Results are estimates for planning only.

What this calculator does

Laundry rooms add humidity from warm water and venting, which can lead to musty air and mold. This tool sizes a laundry room exhaust fan in CFM from the room volume and an air-change target similar to a bathroom's.

How to use it

  1. Enter the laundry room's length, width, and ceiling height.
  2. Use about 8 air changes per hour, similar to a bathroom.
  3. Read the required CFM and pick a fan to match (at least the small-room minimum).

The formula

Volume = length × width × height. Airflow (CFM) = volume × ACH ÷ 60. A 50 CFM minimum is common for small rooms.

Example calculation

An 8 ft × 8 ft laundry room with 8 ft ceilings at 8 air changes per hour:

  • Volume: 8 × 8 × 8 = 512 cu ft
  • Airflow: 512 × 8 ÷ 60 = 68.3 CFM → 69 CFM
  • Metric equivalent: about 117 m³/h

Result: About 69 CFM — a 70–80 CFM fan comfortably handles laundry humidity.

Buying and planning tips

  • A dryer must vent outdoors through its own duct — the room fan does not replace it.
  • Run the exhaust fan during and after wash cycles to clear humid air.
  • Keep the dryer's duct short and lint-free for safety and efficiency.

Common mistakes to avoid

  • Assuming a room fan can substitute for a proper dryer vent to the outside.
  • Undersizing the fan and leaving the room damp and musty.
  • Neglecting the dryer duct, which is both an efficiency and a fire-safety issue.

Assumptions and limits

  • About 8 air changes per hour is a common target, similar to a bathroom, not a universal code value.
  • The dryer's own vent to the outdoors is separate from this room ventilation.
  • This is a planning estimate only — check local code and the fan's rated airflow.

Frequently asked questions

How much ventilation does a laundry room need?

Size by volume × ACH ÷ 60 at about 8 air changes per hour. A small 8×8 ft laundry room needs roughly 70 CFM.

Does the dryer vent count as ventilation?

No. A dryer must vent its hot, moist exhaust outdoors through a dedicated duct. The room exhaust fan handles ambient humidity, not the dryer's output.

Why ventilate a laundry room?

Washing and venting add humidity, and a damp, poorly ventilated room invites mold and musty smells. A fan keeps the air dry.

How big should the laundry fan be?

For most small laundry rooms, 70–80 CFM is plenty. Size larger rooms by air changes per hour, and never go below the common 50 CFM minimum.

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