As the curtains are already sewn I can't do a step by step photo tute but rest assured, they're so easy it doesn't matter. It will take you longer to figure out the measurements than make the actual curtains!
Determine the size you'd like your curtains to be:
Base your measurement on the curtain pole rather than the actual window. Then adjust by the factor of how gathered you'd like your curtains to be. Some people like the curtains to be ruffled even when they're closed. Not me, I like them kind of blind-esque but with enough extra that they easily pull shut. My window is 42 inches wide, my pole 72 inches and I made two curtains each 37 inches wide. If you want them more ruffled, obviously increase the width! Add 1" to each curtain's width to represent a seam allowance of 1/2" to the left and right sides.
Height and tabs:
Measure from where your curtain pole is to the distance below your window where you'd like the curtain to end. For me, I wanted the curtains to roughly end where the base of the window sill is so they don't interfere with whatever furniture we have below the windows. My window is 41 inches tall, the extra distance up to the pole and down to the base of the sill is 10 inches so my total curtain height (including tabs) is 51 inches. The tabs should be long enough to slide relatively well but not so long that you see actual window at the top. By measuring from pole to two inches above the window, I determined that my tabs should be 5 inches high. Subtract the tab height back out of the curtain height (51" less 5") and the curtains not including tabs will now be 46 inches tall. Add 1" to your height to represent a seam allowance of 1/2" to top and bottom side.
The tabs' finished height of 5 inches should be doubled as they are folded over. The width is again up to you, I used a finished width of 2.5 inches which is chunky and sturdy enough to cope with the fabric's weight. The number of tabs will depend on the width of the curtains, but aim for about 4 inches apart. With seam allowance added to all four sides, each of my tabs measured 3 inches wide (using 1/4" SA each side) by 11" long (using SA of 1/2" to top and bottom).
Summary of all pieces required for one window measuring 42" wide by 41" tall:
Two pieces of curtain fabric 38" wide by 47" tall
Two pieces of lining fabric 38" wide by 47" tall
14 pieces of curtain fabric 3" wide by 11" tall
14 pieces of lining fabric 3" wide by 11" tall
- Cut your pieces identically for both lining and curtain fabrics.
- Prepare the tabs first. Right sides facing, sew the curtain fabric to the lining fabric at both long edges, leaving the short edges open. Repeat for all tabs. Turn all tabs right side out and press flat. Optional: topstitch along right and left (long) sides.
- Fold the tabs in half, matching up the short ends with the curtain fabric facing out. Baste the short ends together close to the edge so they are even and don't slide about. Repeat for all tabs.
- Right sides facing, lay the main curtain body on top of the lining body. Facing down into the curtain, place the tabs inside the sandwich between the curtain and lining fabrics, ensuring they are evenly spaced. It helps to align the basting line of the tabs with the top edge of the curtain so they are sticking out a bit so you can see exactly how they are spaced. Pin in place. Also pin along the two sides and the bottom, but leave an opening of approximately eight inches near the top of one of the sides. Don't put it right up to the corner or you'll regret it. If you're using particularly heavy fabric, leave a gap of more than eight inches as you need to be able to pull the whole curtain through this gap.
- Starting at the top (tabbed) edge, sew all the way around the curtain using a 1/2" seam allowance, pivoting at the corners. Remember to leave that hole open or you will cry a million tears. Repeat for second curtain.
- Clip your corners at 45deg angles so you get them nice and sharp.
- Pull the right sides out through the hole and press flat with an iron. The tabs are now out and facing the right direction. The opening that you pulled through will naturally fold under along the seam lines that you already sewed so press them flat and pin in position.
- Topstitch all the way around the curtains close to the edge, giving them a nice finish and also closing your gaps. You're done! Hang them up and watch your life improve.