It is normal for curtains to touch the floor. Some styles even need more length to produce a certain look. Using any of the curtain length styles is fine as long as it enhances the beauty of your home.
Just Hitting the Floor or Sill
The fabric should just touch the floor or hover 1/2 inch above. This is also a great approach for café curtains (short panels that cover only the lower portion of a window and hit the sill), which work well in spots like the kitchen and bathroom, where long drapes aren't practical.
While fashion used to suggest a “flood level” bottom line for curtains—one that hung just beyond the window sill and was short enough not to get wet in a flood event, these days, style dictates that curtains should drop to about 1/2-inch off the floor or even puddle slightly.
To make sure your short curtains are in style, however, be sure that they extend no more than 3" past the bottom of your windowsill. Curtains that reach halfway between the windowsill and the floor typically look awkward and dated.
For the ideal middle ground, curtains should hover just above the floor. To find the right curtain length, measure from the floor to where you'll hang the rod (usually 4 to 6 inches above the window frame).
Standard curtains typically hang from about a half-inch from the floor to halfway between the window trim and average-height ceiling. But to maximize visual height, let the walls determine your curtain's length; in a living room, library, den or bedroom, the longer the panels, the better.
When hanging curtains, it is important that the curtains are the right length. Curtains that are too short make the room look short, stubby and awkward. The cut the length of the wall, making both the window and the room look smaller. An example of curtains that are way too short!
In this case if you hang a curtain too high it could look a little off, especially if there is a lot of bright light coming through showing where the actual window is. In that case you should hang them about 8 inches or less above the window frame.
Floor length curtains usually don't touch the floor. Because of this, your curtains will hang straighter and look cleaner. We use this type of curtain length on high-traffic areas such as the living room. It is both practical to use and beautiful to look at.
Tip: Traditionally, you'd mount your curtain rods one to three inches above the top of your window frame. But my favorite trick is to hang your curtain rod higher (a couple inches below the ceiling). It'll instantly make the room feel taller and grander.
When you buy them in stores or online, there are two standard lengths: 84 inches and 95 or 96 inches. The length of the curtain dictates the height of the rod. If you buy 84-inch-long curtains, the rod must be mounted roughly 84 inches from the floor if the curtains hang from the rod without rings.
Tiebacks slightly shorten curtains. This is why they don't work well with short bedroom curtains. Since shorter curtains form a small bundle when compacted, they look less appealing with the use of tiebacks. So, if you want to pull off short bedroom curtains, push them to the side instead of tying them.