CFM stands for cubic foot per minute and is an essential for when you are choosing a fan for your bathroom. It’s usually labeled on the product and are largely accurate. It is recommended that when you are choosing a fan that you take into consideration the size of your bathroom as this will help you determine which fan to buy. Based on your bathroom’s size it should have airflow of one cubic foot per minute to every square foot. If the bathroom is bigger than 100 square feet, it is generally better to get two smaller fans for the space.