Agricultural Extension Standard • Flock Health & Frostbite Prevention
Chicken Coop Ventilation & Sizing Calculator
Size your coop vents, gable louvers, and floor space accurately. Prevent moisture, frostbite, and toxic ammonia buildup for any flock size.
🐔 University Agricultural Standards
Chicken Coop Ventilation & Sizing Calculator
Moisture & Ammonia Prevention
8 Birds
2 Hens6 Hens (Backyard)12 Hens24 Hens40 Hens
Total Ventilation Required
--sq. inches
-- sq. feetHigh Outlets (Gables):-- sq. in.
Low Inlets (Intake):-- sq. in.
Min. Coop Floor Space:-- sq. ft.
Continuous CFM Airflow:-- CFM
🛡️ Predator-Proofing & Airflow Rules
- • Never use chicken wire: Raccoons and weasels tear through chicken wire. Cover all vents with 1/2" 19-gauge welded wire mesh.
- • Keep vents ABOVE roost bars: Ammonia and moisture rise. Vents placed high in the roofline prevent cold drafts blowing on sleeping birds.
The 60/40 Ventilation Rule
Proper passive airflow relies on natural convection (the chimney effect). Hot, humid air and ammonia rise naturally, while cool fresh air is drawn in from below:
- 60% High Outlets (Soffits, Gables, Ridge Vents): Placed at least 12 to 18 inches above the highest roosting bar so rising moisture escapes without blowing cold air across sleeping birds.
- 40% Low Inlets: Placed low near the floor (but high enough to avoid deep bedding spills) to draw in fresh replacement oxygen.