While fashion once dictated a “flood level” bottom line for curtains—one that hung just past the window sill, short enough that it would not get wet in a flood—today, style calls for curtains to either hang down to within ½-inch of the floor or even puddle slightly.
A common rule for displaying curtains properly says the curtains finished width should be at least 2 times the width of your window (if not more - sheers can be 3 times the window width) to achieve a look of proper fullness.
The material should barely touch the floor or hover half an inch above. Use this approach for café curtains, too, short panels covering only the lower portion of a window, hitting the sill, which works well in kitchens and bathrooms, where long drapes or curtains aren't practical.
The proper position is ½ inch above the floor for free hanging curtains. This distance allows for mopping and cleaning while creating the illusion that the curtain touches the floor.
Hanging long drapes on a short window is one of the easiest ways to increase the importance of the window and bring it into proportion to the room. Short drapes on a short window call attention to the size of the window and reduce the significance of the room, window and drapery style.
The answer to this question is important because it can affect the way we do our decorations. Yes, curtains should be long enough to touch the floor. With a few exceptions, the longer the curtains are the more stylish and elegant it will look. This is why most standard ready-made curtains are lengthy.
Standard curtains come in three lengths—84 inches, 96 inches, or 108 inches. "Generally, you want to stay away from the 84 inch standard curtains unless you have very low ceilings.
Short curtains are typically only used when long curtains are unrealistic (such as when a radiator, the bed headboard, or some other object would interfere with the curtains). In addition, long curtains provide a better aesthetic and can make the room appear bigger, especially when hung higher than the window frame.
Floor length: Long curtains that go from above your window frame all the way to the floor to create a traditional, formal look. Typical curtain length for this style is 84 to 96 inches; these curtains will fall about 1/4-inch above the floor.
How High to Hang Curtains. A rule of thumb (from Architectural Digest) is that curtains should be hung between four to six inches above the window frame, so install your curtain rod accordingly. When you hang the curtain rod high, it will make the window appear taller.
As a general rule of thumb, curtain width should be two to two-and-a-half times the width of the window. Curtains are typically sold as pairs, but you may need to double up depending on the size of your window.
Hovering an inch or less above the floor
This option is also more forgiving than those that precisely hit the floor, which means your measuring and hemming won't be derailed if it's a few millimeters off. It also means you don't have to worry if you have slightly uneven floors.
If you have the space between the top of your window frame and the ceiling or crown molding, though, you should hang the rod over the window. I like to go 3 to 5 inches down from the ceiling. Doing this visually extends the length of your wall, making your ceiling look higher.
Making Your Room Look Larger or Smaller with Curtains
High-hanging curtains with long vertical stripes create the illusion of height, which is excellent for low ceilings. However, short curtains and horizontal stripes shorten your wall height and make the room appear smaller.
Short Curtains
Visually speaking, high-water style is not the most appealing way to hang curtains. The shorter length can appear dated. Also, it can cut the visual height of your room in half. From a purely practical standpoint, however, short curtains are sometimes the best option.
If you want a little bit more length out of your panel, ring clips are a great way to add 1-2 inches, since the clips means the fabric hangs just below the drapery rod.
While the curtains are still hanging, fold the bottom of the curtains under to the desired length. Use the stick pins to hold, to keep it folded and in place. Bring the curtain bottom up to the ironing board and iron a crease on the new fold. Cut off excess curtain a couple of inches past the fold and remove the pins.
Measure the Width
If you want your curtains to close and cover the entire window: Measure the width of your window. Add 12 inches to each side, 24 inches total. Take the total number (width plus the number you added to each side) and divide that number by how many drapery panels you want in the window.
Floor-length sheers should end one to two inches above the floor if they are hung beneath another curtain. However, sheers can go to greater lengths if they stand alone. For a soft and romantic look, add an additional three to four inches for "breaking" sheers, or 12 to 15 inches for sheers that puddle.
For a 60 inch (152.4cm) window, you need curtains with a finished width at least 1.5 times that, but better are those with twice that width and even three times the width for sheers. Therefore, for a 60 inch window, you need two panels of 60 inches each for twice the width and a luxurious gather.
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.