If you can’t find a zipper that is the perfect length, purchase a zipper that is slightly longer than the seam opening you want to put it in. [1] X Research source This will give you some leeway in positioning the zipper and will help you avoid hitting the end stop of the zipper with your sewing needle, which would break it.
Zippers with metal teeth can stand up to more heat from an iron.
This may seem counterintuitive but remember that a basting stitch is only temporary. It is used here simply to keep your seam in place. You will remove it after you have attached your zipper.
Any excess zipper that is laying below the end of the seam is not a problem. You want a little bit extending down, perhaps an inch or so, but any length in excess of that can be removed. Just cut off the excess zipper before you pin the zipper on and whip stitch the end to make a zipper stop.
You will need to finish the sewing by putting a line of stitches across the bottom of the seam. This will give your zipper an end point which the pull cannot go below.
When taking out your basting stitches, be careful not to snag thread in your fabric or any of your permanent top stitches. A seam ripper is a great tool but it can easily cut threads that you don’t want it to, so be careful.
