Most people hire a professional to measure how many square feet of flooring they will need for their installation. However, if you want to do it yourself or get a rough estimate, here are the basic steps.
Simply put, to determine a floor's square footage for your flooring order, multiply the length of the room times the width and round off inches to the nearest foot. If you have any irregularly shaped floors, you can divide them into individual sections, calculate the square footage of each one, and then add the sections together.
Keep in mind, you do not want to account for areas with permanent fixtures such as cabinets or islands. However, you would need to measure for areas under appliances.