Designing and making you own curtains will save you a lot of money considering how easy it is to do. Fabric can be purchased inexpensively and there are wide assortments of fabrics available almost everywhere. Large department stores now carry a huge selection of crafts and sewing supplies, so you can be as creative as you like. You will need to know how to figure how much fabric you will need to buy, but that is a simple process.
Measure your windows from side to side or horizontally, including the frames. For a curtain with lots of pleats and plenty of coverage, this measurement will be half the size of one panel. You will need to make two panels for each window. For instance, if your measure across the window is 36 inches, since it is half the size of one panel, double it and you will get 72 inches for each panel.
Take the measurement from the top of the window frame to the bottom window sill. Add 10 extra inches to the top for seams and hems and as much to the bottom as you want the curtain to hang below the window. For instance, if your window is 60 inches, add 10 inches for the top and let's say 12 inches for the bottom, your total length would be 82 inches.
Determine how many panels you need at two for every window. Now multiply the number inches long, 82, (as explained in step 2) by 2 and you will know you need 164 inches or 13.6 feet or 4.5 yards for the length of two panels per window, in our example.
Look at your measurement for the width of each panel. In our example, it was 72 inches which is more than the typical width of 45 inches of fabric sold by the yard. This means instead of one length, you will have to get two or double the amount of yardage you figured for the length in step 3. (Two sections at 45 inches each would give you 90 inches in width which is more than enough for the 72 we figured in this example) If your windows are very wide you might have to triple the amount.
Come to a conclusion by multiplying the number of yards figured for the length in step 4 by the number of widths figured in step 5. In our example we have 4.5 yards multiplied by 2 which means we need 9 yards of fabric for each window. This number can be adjusted once you understand the formula to make the width more narrow or wider for each panel.
If in doubt, ask a sales clerk. They are usually pretty good with measurements.