When cutting fabric for your patterned drapes you'll need to go through all the normal checks as described in the section on cutting plain fabric. But then there's just a couple of extra steps to make sure your patterns line up correctly.
There are just two things to consider when you come to cutting fabric with a pattern.
It's very unusual for your pattern to fit perfectly so you have a full pattern at the top and the bottom of your finished length. More often the pattern will be incomplete. An incomplete pattern is usually less obvious at the heading than at the hem, so start the first complete pattern just above the hem line, as shown in the illustration (line AA).
Mark off the hem allowance.
From the bottom of the hem allowance measure out the cut length (the cut length is the finished length + the hem and heading allowances).
In most cases this will end up in the middle of a pattern repeat. Whatever the situation, adjust your cut length so it is a multiple of the pattern repeat.
In this case the adjusted cut length is equal to three pattern repeats.
All the cut lengths have to begin at the same point in the pattern so the seams match up when you join them.
(Remember when measuring for a patterned fabric you rounded up the cut length to a multiple of the pattern repeat? And then added an extra pattern repeat? Now you can see why. The extra pattern repeat gives you the leeway to make sure the pattern begins at a suitable place near the hem. Go back to the measuring page if you want a reminder of how it's done.)
When you adjust the cut length to be a multiple of the pattern repeat, be careful that you move up by a whole pattern repeat. Some pattern - especially geometric ones - can be tricky.
Once you have your adjusted cut length you can now mark out the remaining cuts. Remember to mark them out first, to make sure you have allowed enough material.
When you're cutting fabric for patterned drapes just take your time. Don't cut any fabric until you're sure that you understand which panels are going to join up with each other. Once you're sure, mark them so once they are cut you'll know which ones go with which.