How to Sew a Centered (Slot) Zipper

In this article, you will learn how to install a centered (slot) zipper. It’s as easy as this: Partially, sew the center back (CB) seam and press it open. Topstitch down the right side (RS) of the zipper, pivot, sew across the CB seam to the other side, pivot, and sew up to the top edge of the garment. And your zipper is in!

Truth is, the first centered zipper I attempted to sew ended in a lake of tears, a ruined project, and almost made me give up on sewing. Yes, it was that traumatizing!

But now I know, it wasn’t me! It was the crappy instructions included with the zipper and the lack of any skill building practice! Silly, silly me.

Here’s the thing…

I refuse to let that happen to you!

So let’s start with the anatomy of a zipper, a few bonus tips, and then learn how to sew in a centered zipper step-by-step with images…

NOTE: If you’re ready to begin this journey and would like to buy my recommended tools and supplies, please click HERE!

Zipper Anatomy

All zippers share the same anatomy. In the image below, we have a close-end zipper

Zipper Anatomy - Stitching in Colour
  • Stops: There are two stops at the top and one-stop at the bottom. These prevent the slider from coming off the zipper chain.
  • Teeth or elements: When the zipper is unzipped, they reveal teeth on each side of the zipper tape. These teeth can be metal or nylon.
  • Chain: When the right and left zipper teeth are entwined, they become the chain.
  • Tape: this is the length of woven fabric on either side of the zipper teeth or chain. It can vary in weights and fabric types, but it is usually made from polyester.
  • Slider + Pull tab: This is what you pull on to zip and unzip the zipper. The pull tab is attached to the slider — the slider moves up and down the chain, zipping and unzipping.
Closeup Zipper Slider and Pull - Stitching in Colour

Zipper length: This is measured from the two top stops at the top and the stop at the bottom. It is NOT from the one end of the zipper tape to the next!

Now, that you can identify the parts of a zipper, let’s learn about…

Zipper Feet

You can sew in a centered (slot) zipper using a standard or narrow (ski-style) zipper foot.

Zipper Presser Feet - Stitching in Colour

The standard zipper foot (on the left) is usually included with the accessories of modern sewing machines.

But the narrow zipper foot (on the right) typically has to be purchased separately.

Inserting any kind of zipper is easier with the narrow style zipper foot because it allows you to stitch close to the zipper teeth without any fuss! It is a worthwhile purchase!

RELATED: Click HERE if you want to learn more about zipper feet and the other basic presser feet!

And as promised, here are some…

Zipper | Bonus Tips

  • A centered (slot) zipper application can be used in skirts, tops, and dresses.

For ease of application, buy a zipper that is at least two (2) inches longer than you need. This will allow you to keep that bulky slider + pull tab out of the way, so you can sew in your zipper smoothly and with the absolute minimum of frustration.

  • Plus, using a too long zipper and cutting off the excess AFTER finishing the waistline and neckline edge eliminates the need for a hook & eye! I sort of hate hook & eyes, so for me, this is a big win!
  • With nylon teeth, you should have no worries cutting off the excess AFTER you’ve finished the waistline or neckline edge!

To strengthen the zipper opening, ALWAYS interface the zipper opening with a strip of interfacing or silk organza.

  • Skirt zippers are usually from 7 to 9 inches long. And dress zippers can be 14 to 22 inches long.

So now that you know the anatomy of a zipper and are privy to these bonus tips, it’s time to learn…

How to Sew in a Centered (Slot) Zipper

Listen, there are probably a zillion methods of installing a centered zipper. I’ve tried many of them — and this is my fave. Let me count the reasons why I love this method:

  • No excessive pinning
  • No gluing
  • No sticky tape
  • No basting to unpick

Excited?! Great!

Now, before we begin, inhale and exhale slowly, and then vow to approach this skill with confidence and just a tiny bit of patience…

Step 1. Mark the bottom of the zipper.

When you cut out the pattern pieces, make sure to transfer the notch at CB to the fashion fabric of where the bottom stop of the zipper will be positioned.

In the image below, I used a blue water-soluble pen to mark the position of the bottom zipper stop for a size 10 garment.

Marking Bottom of Zipper on Garment - Stitching in Colour

Step 2. Interface the SAs of the zipper opening.

First, cut two strips of fusible tricot interfacing that is 1 inch wide and 1 inch longer than the zipper opening. You want the interfacing to overlap the zipper’s seam line.

Interfacing the zipper opening improves stability and prevents distortion and rippling over time!

Now, fuse one strip to the zipper opening at the garment FRONT and the garment BACK.

Zipper Area Interfaced - Stitching in Colour

Once the interfacing is fused to the zipper opening, go ahead and transfer the construction marking to the interfacing of where the zipper’s bottom stop is to be positioned.

Step 3. Finish the SAs of the zipper seam (not shown).

Finish the SAs BEFORE you sew in your zipper. Choose the seam finish you prefer or what is appropriate for the fashion fabric used in the project. Options include zigzag, pinking, or serging.

But for accuracy and ease of insertion, do NOT trim off any of the SAs!

Sew easy tip: If I choose to pink the raw edges, I mark the 5/8 inch SA at the zipper opening BEFORE I pink the edges. This way I make sure I sew the CB seam using the correct SA.

Okay, it’s time to…

Step 4. Partially sew the seam where the zipper will live.

Using a regular stitch length, with the right sides together (RST), sew the seam, from the hem of the garment up to the point where the bottom stop of the zipper is to take up residence.

Make sure to backstitch where the bottom of the zipper will reside. Because that area will be under a lot of stress during the life of the garment!

This is point where you need to backstitch!

Step 5. Press the SAs open.

Press the SAs open all the way up to the top edge, which is typically a neckline or waistline edge.

Step 6. Mark a topstitching guideline.

Choose a  marking tool that can easily be removed without leaving a trace!

Then,  from the RS of the garment, mark a topstitching guideline on either side that is ¼ inch from the zipper seam and ¼ inch below the bottom zipper stop.

Okay, get ready to be impressed by how easy a centered zipper is to sew into a seam.

Step 7: Align the zipper with the zipper opening.

Now, with the zipper facing RS up, position the bottom zipper stop slightly above the bottom of the zipper opening of the garment.

AND THEN…

Align the right zipper teeth with the right fold of the seam.

If the fold of the seam is positioned properly over the zipper, you will NOT be able to see the zipper teeth from the RS!

Zipper Teeth Aligned with Fold - Stitching in Colour

Anchor the zipper in place with a single straight pin. This step is optional, but I find it helpful.

Sew easy tip: I like to use a zipper that is longer than required so that the zipper tape extends at least 1 to 2 inches above the top edge of the garment’. This will make for an easier and prettier installation!

Guess what?! It is time to…

Step 7. Topstitch the zipper in place.

Install your zipper foot on your sewing machine with the needle positioned on the LEFT.

Before you begin, MANUALLY lower your needle to make sure it is far enough left to clear the zipper foot!

Center Zipper Positioned to be Sewn - Stitching in Coloiur
Zipper teeth and fold are even or flush with each other!

Now, lower your presser foot and press the needle down button.

Using a regular stitch length for your fashion fabric, backstitch at the start, and then stitch forward towards the bottom of the zipper. 

As you stitch the first side of the zipper in place, make sure that the zipper teeth remains even or flush with the fold of the zipper opening all they way down to the first pivot point.

When you are about 1 inch from the bottom, STOP with the needle down and zip up the zipper all the way to the top edge.

Then, continue to sew past the bottom zipper stop — you so don’t want to sew over that hard and unyielding zipper stop!

And when you reach the corner, pivot.

Now, sew across the CB seam to the other side and pivot again at the other corner.  

Finally, sew up to the top edge of the zipper opening on the left side (LS) of the CB seam.

Again, make sure that you cannot see the teeth of the zipper as you complete the second side of the zipper insertion!

Center Zipper Sewing the Opposite Size - Stitching in Colour
The zipper teeth are completely hidden!

Step 8. Press.

Take your garment to your ironing board and give that zipper seam a quick press. And voilà!

Your zipper is in and pretty!

Super Bonus Tip

Once your zipper is sewn into the CB seam, you can finish your neckline or waistline edge…

Keep this in mind: Once the zipper is installed, do NOT cut off the zipper excess at the top BEFORE finishing your neckline or waistline edge!

Because if you do, the zipper’s slider + pull tab might come off the zipper teeth/chain. Then, you will need a new zipper, have to unpick the useless zipper, and repeat the zipper insertion process again. And you’ll be pissed!

Zipper Pull Off - Stitching in Colour

And one last thing…

How to Shorten a Too Long Zipper

If your zipper is too long, you can shorten it. And if you need a zipper in a non-standard length, you can create a custom length. It’s sew easy!

Take your extra long zipper, whipstitch a new bottom stop at the desired length, and then cut off the excess with pinking shears to help stop fraying. Here’s an image from a Coats & Clark zipper packet on how to do just that…

Shorten Zipper How To - Stitching in Colour

Sew easy tip: You can use an extra-thick thread like topstitching thread instead of a double-strand to whipstitch!

THE END

That is how easy it is to install a centered (slot) zipper: No excessive pins, no glue, no sticky tape, no basting stitches to unpick, no fuss!

And remember this…

Life is the ultimate red carpet event! Dress for it!

RELATED: Click HERE to learn how to install the super-strong lapped zipper!

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