Typically synthetic fabric is 60" wide. That hems down to between 56-58" . Wider fabric is available from certain mills depending on the application for which it was made.
Natural fibers are typically woven 36-44" depending on the specific fiber. Silk can run narrower than cotton or wool for example. Just the nature of the industry.
By joining panels you can make the width as wide as you want. By trimming the panels you can make it as narrow as you want. There are no standards etched in stone to my knowledge.