Exhaust Fan Sizing Calculator

Calculate the exhaust fan CFM rating needed for bathrooms, kitchens, or utility rooms based on room volume and required air changes.

ft
ft
ft
ACH

Fan Rating Needed

85 CFM

कमरे का आयतन640 cu ft
CFM per Sq Ft Rule80 CFM

Fan Rating Needed vs Room Length

सूत्र देखें →

सूत्र

## Exhaust Fan Sizing **CFM = Room Volume x ACH / 60** The HVI (Home Ventilating Institute) recommends a simpler rule for bathrooms: 1 CFM per square foot for rooms up to 100 sq ft, and 50 CFM minimum. For larger bathrooms, add 50 CFM per fixture (toilet, shower, tub). Kitchens need 100-400 CFM depending on cooking.

हल किया गया उदाहरण

10 x 8 ft bathroom, 8 ft ceiling, 8 ACH.

  1. 01Volume = 10 x 8 x 8 = 640 cu ft
  2. 02CFM = 640 x 8 / 60 = 85 CFM
  3. 03Square foot rule = 80 CFM
  4. 04Use at least an 80-90 CFM fan.