The most important thing you need to know before buying chickens for your backyard chicken coop is whether your local law permits you to raise chickens. There isn't one Utah law that applies to the entire state. Rather, if you live within city limits, check to see if your city code has any laws about raising chickens; if you don't live within city limits, check the county code.
For example, in Salt Lake City, you must first apply for a permit from the office of animal services in order to raise chickens and the fee is $5/animal. Salt Lake City Code 8.08.010. A permit will not be granted for more than 25 chickens. Salt Lake City Code 8.08.020. Different rules apply to people who want to raise chickens for commercial purposes. However, no animals may be housed closer than 50 feet from a building used for human habitation. Salt Lake City Code 8.08.060.
Another example of local laws regarding chickens is found in the Brigham City Code. Brigham City residents may keep up to six chickens but the chicken coop may not be larger than 50 cubic feet per household. Brigham City Code 4.01(16).
Another example is found in the Vernal City Code. In Vernal, if property has been zoned RA-1 (residential-agricultural), up to 25 chickens may be kept on a lot that is at least 20,000 square feet. Vernal City Code 16.38.020. However, if other animals are kept on the same lot, that number decreases.
To find your city or county code, begin at the Utah.gov page and then select your city or county. Once directed to the city or county's page, you'll need to locate the code. Local codes are sometimes referred to as "municipal ordinances" or simply "ordinances." If you can't locate the code online, contact your local government.