Window window curtains (A fenestral masker aid)

Posted on 10 Oct, 2018

This post contains a pattern and spottily-documented instructions for how to sew some window curtains that I designed to look like windows.

Why make curtains that look like windows, when you could just not make the curtains and instead look at the windows directly?

We will have to think about that.

The curtains

I think the curtains turned out well. They block out nighttime light, they provide privacy from prying neighbor eyes, and they look pretty nice. I can usually tell that they're not windows, but it's a close one. Unfortunately I didn't take any pictures while I was sewing, so besides these two, all the images are just diagrams.

Closed curtains
Open curtains


I used two colors of fabric for this project: A small piece of blue and green batik that my mom gave me, to represent the sky, and a queen-sized purple comforter cover that I got from Goodwill, to represent the window frame and for the second (back) layer of the curtains.

You will also need basic sewing things like: thread (mostly any color; only one seam is unhidden), scissors, a sewing-machine (or a needle and a lot of patience), and a way to make measurements. An iron is also nice to have.


I made the diagram below in QCAD before cutting the fabric. Although I didn't necessarily follow it. But you could!

A universe with only one constellation: The Grid. Watch out for Trisolarans.

The design depicts a double set of windows, where each window has a fixed top section and a vertically sliding lower section, and each section is divided into two vertical panes. On my actual windows, the sections are each only one pane, but I had a lot of purple and not enough blue, so had to overstate the frame situation. The left window is mostly open while the right window is about halfway open.

The ordering of the horizontal and vertical bars and seams, when they cross, is meant to indicate which panes are in front and in back. So the lower, sliding section of each window is closer to the viewer while the upper, fixed section is behind that.

Not shown in the design above are the straps that the curtain rod goes through, nor the back side of the curtains, which are each just a single piece of fabric the same size as the finished front side.


Figure A, below, uses the lefthand window as an example and shows all the pieces put together. Figure B shows each piece separately with its dimensions labeled in terms of x and y, explained in Figure A and in the dimensions section below.

Figure A: Click to see full-sized image
Figure B: Click to see full-sized image


Purple (frame) fabric: Pieces A, B, C, D, E, F, G, H, I, J, K, L, M, N.
Blue (sky) fabric: Pieces P, Q, R, S, T, U, V.


This section is a convoluted algebra problem that describes how the pieces should be proportioned to each other, based on the size of the real window you want to cover, and on how open/closed you want the curtain-window to look. Rule of thumb: make everything a little wide, since a ripply closed curtain is better than a closed curtain without full window coverage (as the saying goes). Units are inches, seams are 1/2".

  1. Measure your window.
    • x = The width between outer edges of the outer frame (ie just before the wall).
    • y = The height between the outer edges of the top and bottom of the inner frame.
    • L and M can be whatever height is needed to make things work out in the end.
  2. Figure out the relative heights of the window-pane pieces, which depends partly on how open or closed you want the window to look. Since the panes are symmetrical, I will just talk about the heights of pieces P, R, T, and V (on the left side). I'm not sure what will seem like the most obvious way to think about this for other people, but here's one way:
    • Window-frame pieces measure either 2" (F, G, H, I, J) or 3" (A, B, C, D, E, and K) in their narrow dimension.
    • The total height of the window (both sections) is y - 3.
    • The lower (sliding) section of the window should be 2" taller than the upper (fixed) section. But, when the window is closed, bar I overlaps with bar F, and 2" of K gets nested behind the sill. (P+R+4)=(T+V+5)=(R+T+7-2)=(y/2-1.5)
    • Since the total section heights are all equal, and frame piece K is 1" taller than its compatriots (pieces I and F), that makes the pane for the sliding section 1" shorter than its pane-colleagues. Specifically that inch should be taken off the bottom of the pane. P=T+1
    • It follows that R=V
    • In my opinion, it looks weird for any section of window-pane or open window to be as narrow as a section of window-frame, so, all heights >= 3.
  3. An example where your windows are 63" high (y) and you want the curtain-window to only look a little bit open, let's say 4":
    • V = 4
    • R = 4, since R = V
    • T = 21, aka 63/2 - 1.5 - 4 - 5
    • P = 22, aka T + 1
    • (Add 1" to all heights for the 1/2" seams on either side.)
  4. Fill in your chosen heights for the missing measurements in Figure B and cut your pieces, except L, M, and N.


  1. Sew together inner pieces: PHQ, RFT, SGU, KV.
  2. Connect intermediate inner pieces: RFT to J to SGU; PHQ to I.
  3. Connect all inner pieces: I to RJS; K to TJU.
  4. Sew pieces D and E to the long edges of the window you just made.
  5. Sew piece A to the top edge of the window, DPHQE, with 3.5" hanging off each end.
  6. Sew pieces B and C to D and E, respectively, aligned along the bottom but with 3.5" hanging off the top, near A.
  7. Sew the diagonals where A and B meet and A and C meet, then cut off the extra triangles, leaving the 1/2" seam.
  8. Check how high L needs to be: With A aligned with the top of your window (a little below the rod — this will be filled in by M ), measure from the bottom of the curtain to 3" below your windowsill, and add 1" (total) for seams.
  9. Sew L to the bottom of BDVEC.


  1. Iron the front so all seams lie flat.
  2. Cut piece N to be the same size as the finished front.
  3. Sew N to the front along the bottom of L (good sides in).
  4. Sew N to the front down the long edges (good sides in) so you have a giant bag shape. Turn right side out.


  1. Measure the height for your M pieces: The distance from the bottom of the top window frame to the top of the rod. Probably this will be about 1.5-2". Since these pieces get folded in half to go around the rod, double your desired height before adding the 1" (total) for seams.
  2. Figure out how many M pieces you need and how far apart they will be spaced. They should be 3" wide, and spaced around 2-4" apart. And you want an odd number so they are aligned with the edges of the curtain. I used 1 + (x - 3)/6, rounded whichever way gives you an odd number.
  3. See Figure C for illustration: Measure and cut your M pieces, fold them in half along the 7" edge, and sew down the outer edge. Turn them right side out so you have a series of tubes that are 3" wide. Iron flat such that the seam is in the middle (not along a fold). Fold in half perpendicularly to the seam, so that the seam is on the inside.
Figure C: Click to see full-sized image


  1. Change to a thread color that you don't mind showing. Figure D illustrates steps 2 through 5.
  2. Along the open top edge of your giant bag/curtain, fold down the 1/2" seam allowance on either side in toward the middle and iron down the fold.
  3. Insert both raw ends of the first folded-in-half hanger M piece into one corner
  4. Sew down along the outside edge of the fold. Continue sewing the top curtain edge together for the amount of space you decided should be between M pieces.
  5. Insert the next M piece at the point you stopped sewing and continue sewing until you have used up your M pieces and gotten to the end of the curtain top!
  6. If you have pins you could also place all your M pieces beforehand and pin them down, then just sew one long seam.
Figure D: Click to see full-sized image

Et voila! Congratulations on your new curtains! May no birds fly into them.