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Calculation Machine

Chicken Coop Ventilation Calculator

Vent area and fan CFM for a coop.

Reviewed by the Calculation Machine team · How we check our maths

Your values

ⓘ Live results

Results
Passive vent area
4.8 sq ft
Summer fan airflow
40 CFM
Winter minimum
8 CFM
Air changes at summer rate
8.3
Floor space check
6 sq ft per bird

Quick answer

A coop needs roughly 1 square foot of vent opening per 10 square feet of floor, and 3-5 CFM of fan per bird in summer.

The formula

vent area = floor area / 10; summer CFM = birds x 5

Worked example

Worked example

Using the values the calculator loads with.

Inputs

  • Coop floor area48 sq ft
  • Number of birds8
  • Average height6 ft

Result

  • Passive vent area4.8 sq ft
  • Summer fan airflow40 CFM
  • Winter minimum8 CFM
  • Air changes at summer rate8.3
  • Floor space check6 sq ft per bird

How to use the Chicken Coop Ventilation Calculator

  1. 1Measure the coop floor and count the birds.
  2. 2Put vents high, above roost level, so there is no draft on the birds.
  3. 3Add a small fan for summer heat — ammonia and moisture build fast in still air.

Frequently asked questions

Won't ventilation make them cold?

Chickens tolerate cold well but not damp; moisture causes frostbite, so keep vents open year-round.

Where should vents go?

High on opposite walls under the roof overhang, never at roost height.

About this calculator