First, some vocabulary lessons:
In our world a panel is what we call a finished drape or curtain. Typically windows will have two panels that hang on either side of the window. A width of fabric is how wide it is on the roll (typically 54") and each panel can be made from as little as one width of fabric, but can go up depending on the size of the window and the style of the curtain/drape. And fullness relates to how many widths of fabric it takes to make a panel.
So here we go:
1. Step one is to first decide on the style of drapery you want. We will cover this more in-depth in another blog post, but your basic options are a flat panel (including a rod pocket, gathered on rings, and grommets) or pleated. (Which includes so many variations that we really need to get that other blog post written! Our favorites, however, tend to be a Classic 3-finger or a 2-Finger Euro.) For this example lets decide to do a flat panel gathered on rings.
2. Step two is to figure out your Bracket to Bracket measurement. You do this by measuring where your rod brackets (or track) are to be hung. If you are able to go outside the window frame where the fabric can stack back when the drapes are open, all the better. (We like to go "high and wide" with our draperies!) For this example lets say that the bracket to bracket is 65".
3. Step three is where the math starts happening...multiply your bracket to bracket number by the fullness amount. For most pleated drapes you need 2.5-3 times the fullness. For flat panels gathered on rings or grommets, 2 times the fullness will do. Rod pockets are usually 1.5-2 times fullness. 65" x 2 = 130"
4. Divide the number from step 3 by the width of the fabric you are using (most are 54") and you will get how many widths of fabric you need to make the finished panel. Just a note - if you are between numbers always round up! 130/54 = 2.41 - so 3 widths are needed. (Which means each panel will be made up of a width and a half of fabric!)
5. Now we figure length. As I said before, we prefer drapes to hang "high and wide" whenever possible. Measure from where the rod is going to hang above the window, to where you want to the curtains to end. For this example lets say we want the curtains to finish 93" long.
6. Take the length measurement and add 14" to allow for top and bottom hems. We call this the cut length. You may also have to take into consideration the pattern repeat of the fabric you have chosen. (This is a bit more advanced so feel free to bring the info you have gathered so far and we'll help you from here!) 93 + 14 = 107" cut length
7. You take the number of widths you need (you found that in step #4), and multiply that number by your cut length (step #6). Divide that number by 36 (which is the number of inches in a yard) and that tells you how many yards you need! 107 x 3 = 321" needed. 321"/36 = 8.92. So this window will need 9 yards of fabric!
Of course, all curtains have their unique challenges. We are happy to go over your measurements and calculations to assure a perfect fit!