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.
How wide should curtains be? To ensure that curtain panels look ample when closed, they should have a combined width that is 2 to 2.5 times the width of the window/rod. That means if you are ordering Grommet style or Rod-pocket style, the total drapery width should be at least 2 times the window/rod widths.
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.
Sill Length
1/2" above the window sill. Casual and charming. These are the shortest of the standard curtain lengths, which makes them a good opportunity to have some fun with pattern or color. Since they take up less visual space, you won't get tired of a bold choice.
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.
For a 120-inch window, how wide should curtains be? Depending on the weight of the fabric and how much you want the curtains to be. At least a width and a half is what I would recommend. 180 inches is the width of each curtain.
For example, for a 60-inch window with two curtain panels, add 24 inches to 60 inches (window width) and divide by 2 (number of panels) to get 42 inches. The two panels ordered each need to be at least 42 inches wide.
Curtain measurements are always written with the width first and then the length. For example, a panel that is 46″ x 54″ is 46 inches wide and 54 inches long. Don't buy your curtains just so they're big enough to cover a window.
As a general rule, drapes will be open during the day, so make sure the curtain rod extends at least four inches on each side of the window's inside frame. To create the illusion of a wider window, extend the rod up to 10 inches beyond the window's frame.
In Closing. For a 9-foot ceiling, 96-inch curtain panels are typically a good fit. This allows you to hang curtains that reach the floor, with the rod placed one foot from the ceiling. If you prefer curtains that pool on the floor or curtains that hang higher, just pick the next size up.
To get the measurements, measure the width of the rod from left to right. For instance, if your window measures 72” wide, you will need curtains that will give a maximum width of 144” (window width x 2 = 144”.)
Keep in mind that the width measurement is flat. If you hang a 48-inch panel on a 48-inch window, there will be no fullness or draping. According to Curtainshop.com, finished curtains should be twice the width of the window, so if your window is 36 inches wide, you need panels that are at least 72 inches across.
The standard curtain width is always 2, 2.5, or 3 times the width of the window. So the formulas used to calculate the width of your curtain is: Standard curtain width = width of window × 2. Deluxe curtain width = width of window × 2.5.
Following the rule of thumb, curtains for a 96-inch window should range between 192 and 240 inches wide. To get a fuller look, aim for 288 inches wide.
Example: If your window measures 36″ wide (window width x 2 = 72″), you need curtains that will give a minimum width of 72″ or 2 panels for that window. In this case 2 panels will give about 100″ to 120″ of width which will look nice and full.
For example, if the window is 100 inches wide, the curtains should be made to 125 inches wide in order for them to hang off the window when in the open position. For an inside-mount curtain, measure from one edge inside the frame to the inside edge on the opposite side.
The actual amount of gather depends on heading styles and personal preference, but as a general rule the width of your curtains should amount to double the width of your track. This is referred to as 'two times gather'.
You should choose the width that most closely matches the size of your track or pole. The width measurement actually refers to the width of each curtain in the pair, as you need double the width of your track or pole in curtaining for the gathered effect.
In the US, the standard curtain width would be 54”. But generally, it ranges from 50-58”. Some curtain manufacturers even go for as long as 108”. Again, knowing the curtain width is as essential as the length because you have to align it with standard curtain sizes.
There's a simple calculation to work out how much curtain fabric you need. First, multiply the track/pole width by your chosen fullness (eg. Pole width 150cm x 2.5 = 375). Next, divide that figure by the fabric width, which is typically 137cm (375 divided by 137 = 2.73).
The top of most of our windows are 8ft, and we used 108″ panels almost everywhere. So we hung our curtain rod about 13 inches above the windows. The higher the curtain rod, the taller your window will appear. I recommend to always install a rod closer to the ceiling than the top of the window.
"Extending your draperies from floor to ceiling and from wall to wall surrounding your window makes them appear bigger," explains Francesco Bilotto.
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.
Unless you are using cafe-style curtains, the fabric should fall to the floor. These are the highwater pants of curtains and not a good look.
It is often best to use the 4 to 6 inches above the window trim rule here unless the windows stretch close to the high ceilings. If there is little space between the trim and the ceiling, then hang the curtains from the ceiling.