I’d like to know what is the right amount of fabric to puddle on a the floor.
Curtain length is really a matter of personal preference so there is no absolute answer here. Some people prefer that window treatments hang just above the floor, while others want the drama of a voluminous puddle that requires an additional 18 inches of fabric once it has reached the floor. This is often done to be able to tie the curtains back. On average, however, a puddle is about 4 inches on the floor. If you desire something in between a puddle and no puddle at all, try a break of one or two inches, which is when the fabric just folds onto the floor.