By return do you mean the repeat of the pattern on the length of the fabric? Are the windows in the same room and using the same fabric? If yes, the pattern should also line up around the room, for example, same part of the pattern at the floor if both reach the floor.

Don't do just 1 width. A fuller bunched up drape looks better than a skimpy stretched out drape. I've never regretted doing a fuller drape, but always wished I had gone fuller when I've been conservative in the width.

A few more questions before I calculate. If the values you gave are the finished lengths, how much do you want to add for the header and the hem? Are you making them yourself?

I added 16 inches for the header and hem. I really don’t want the drapes to be more then 1.5 and 1 in the width as my view is very beautiful. And there is no wall space for the drape. The windows are in dormers so the drape will hang in front of the window. The drapes are in adjoining rooms.

I am not making them myself. A friend that is a designer is going to send them to a work room for me.

By return I did mean repeat, sorry I am not knowledgeable about drapes. I am hoping to do a euro pleat.

I found the below online for you, which may help. Where are you ordering the fabric from? They may be able to guide you.

Basic Drapery Panels

To figure yardage for basic drapery panels, you will need the cut
length (finished length + allowance for your desired hem and rod pocket
size NOTE: Our workroom adds 16") x the number of panels you are
making.If your selected fabric has a repeat, you will need 1 panel at
the regular cut length and then you will need to add the number of
inches in the repeat to each additional panel.

Examples using standard 84" finished length panels:
*Change the number of inches added for hems and rod pockets, as well as repeats, to suit your needs*

Fabric with a 27" repeat:
1st panel - 84" + 16" = 100"
2nd & additional panels - 84" + 16" + 27" = 127"
x 2 panels = 227" (6.30 yards / 7 yards to be safe)
x 3 panels = 354" (9.83 yards / 10 yards to be safe)
x 4 panels = 481" (13.36 yards / 14 yards to be safe)

NOTE: If you are making panels for additional windows, the number of
inches in the repeat must be added to ALL remaining panels to continue
matching them all to the very first panel.

I think about calculating this by doing part of the calculation in repeats instead of yards. I’ll outline the whole thought process so you can double check me!

I’ll start with the 114” finished length.

For 114” you need 5 repeats.

5x27” = 135”. This has 21” extra (135-114), plenty for the hem and header.

Three widths needed, so 3 widths x5 repeats = 15 repeats.

15 repeats x 27” per repeat = 405 inches.

405” divided by 36”/yard = 11-1/4 yards. Your value of 12 yards is fine.

For the 100” length, you still need 5 repeats. Four just isn’t enough with hem and header added.

For this one you only need two widths, 2x5 = 10 repeats.

10 repeats x 27” per repeat = 270”

270” divided by 36”/yard = 7.5 yards. I’d round up to eight.

That makes a total of 20 for the two windows.

Can you be sure when you order that you’ll get a single piece of 20 yards of fabric? Or one piece of 12 yards and one piece of 8? If not, you may need more.

Hope this helps!

Thank you all so much!!

Yes, calculating using repeats is the exact way to do it.