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Adequate space and adequate ventilation are two of the keys to keeping chicken coop odor under control.
The Usual Guidelines
For each adult, standard-sized hen you need:
I like the Deep Bedding/Deep Litter system for keeping odor down, but there are number of systems that work. https://www.backyardchickens.com/articles/using-deep-bedding-in-a-small-coop.76343/

Adequate space and adequate ventilation are two of the keys to keeping chicken coop odor under control.
The Usual Guidelines
For each adult, standard-sized hen you need:
- 4 square feet in the coop (.37 square meters)
- 10 square feet in the run (.93 square meters),
- 1 linear foot of roost (.3 meters),
- 1/4 of a nest box,
- And 1 square foot (.09 square meters) of permanent, 24/7/365 ventilation, preferably located over the birds' heads when they're sitting on the roost.
I like the Deep Bedding/Deep Litter system for keeping odor down, but there are number of systems that work. https://www.backyardchickens.com/articles/using-deep-bedding-in-a-small-coop.76343/