Most zippers are very versatile and can be shortened. They cannot be lengthened though. So the first step to shortening a zipper is to measure twice, cut once, and always leave a little extra room.
Always shorten a zipper from the top.
Coat zipper (Zippers that come completely apart)
( Pic of Coat Zipper)
Coat Zippers separate at the bottom and have a little guide that lines up the teeth. Cutting the excess length off the top preserves the guide at the bottom. If you cut this off your pulls will come off and you’ll have no way to line up the teeth.
(pic of zipper guide)
(Pic of Dress Zipper)
Dress/skirt zippers (invisible and normal) are connected at the bottom. Technically speaking they could be shortened from either end, but for simplicity’s sake and because the manufactured end-stop is usually quite good, follow the same principles.
Shortening the zipper
To shorten a zipper first measure the length of where you want it to go. This coat has a 24 inch opening. Zippers are available that length, but I could only find a 30 inch in the color I needed, so we will be taking 6 inches off the top.
With the zipper closed, line the zipper up with the space. Leave a little extra (in this case about an inch so I can turn the edge under) and snip right through the zipper. Mark where you want the zipper to stop. Plastic zippers will be easy to cut.
(Pic of too-long zipper lined up)
(pic of cut zipper)
**If your zipper is metal be sure not to use your good sewing scissors! Use an old pair or tin snips if necessary. Snip between the teeth if possible.**
Before going any further, separate a small length of teeth at the top and stitch a stop into both sides of the zipper. You can do this by hand, but it’s easier on a sewing machine. Put one side of the zipper under your machine foot where you marked the stop point, pick a nice wide zig-zag, turn off the feed-dogs if you can, and stitch back and forth over your stop mark. Do this for both sides of the zipper. This stop keeps the pulls from coming off the zipper.
(pic of sewn in stop)
Once your zipper is the correct length and has new stops on both sides, test the zipper function to make sure it goes up and down smoothly and meets evenly at the top. If all is well, you are ready to install your zipper!