Most residential range hoods have a CFM between 200 and 600. A higher CFM means your range hood is better at removing smoke and odors from your kitchen. The measurement ultimately depends on your stove’s width and heat output as well as the size of your kitchen. 

Compared to the average size of a stove and kitchen, 350 CFM would be the minimum recommended rating for the average kitchen. However, selecting a higher CFM range hood would guarantee better ventilation to match your cooking habits, whether they’re minimal or extensive.

No, range hoods do not necessarily have to be vented outside. Ductless or non-vented range hoods are available, which are common in condos or small kitchens where connecting to external ductwork isn't feasible. These hoods operate by taking in air, filtering it through charcoal filters to help eliminate smoke and odors, and then recirculating the cleaned air back into the kitchen. However, while these recirculating hoods are more versatile, venting to the outside is still the preferred and more effective method for completely removing smoke, odors, and gases from the room.

By positioning ductwork for optimal airflow and reducing potential leaks.

Smooth galvanized metal ducting is best and safest for venting a hood range. It’s best to avoid flexible and corrugated types of ducting, as these options don’t provide ample airflow and may not meet local code. For specific advice on which type of duct might be best for your kitchen, reach out to a range hood installation professional.