Sewing Expandable Slip Pockets for your bag

If you’ve ever made a bag before, you’ll know that most patterns will include instructions for a flat slip pocket style. If you’ve wished for a style of pocket that would allow more room for bulky items, this tutorial will show you how to create a pleated, expanding slip pocket that can be adapted for most bag patterns.

To start, you’ll need to have your chosen bag pattern ready to sew. Select which inside lining piece you’d like to add pockets to. For this tutorial, I am making a simple boxed tote so my lining piece looks fairly simple:

Determining the size of your slip pocket pieces

Depending on the size of your lining piece, you will need to decide what size to cut your slip pocket lining pieces. I decided that a height of 8 inches would allow my pockets to fit comfortably between the bottom boxed corners and the top edge of the bag.  

I have prepared a diagram to illustrate how I determined the width required for my pockets to fit all the way across the lining piece but also include pleats to make them expand.

Figure 1 : Pleat marks

Since this bag is quite wide at 17 inches, I can easily fit 3 slip pockets. From left to right, they will be 5.5 inches wide (mark A to B), 4” wide (mark C to D) and another at 5.5 inches wide (mark D to F).

To make the pockets expand, I need to add 3 inches of additional width between each set for the pleats, totaling an additional 6 inches of fabric. These are shown as the 3-inch spaces between marks B and C and then marks D and E.

Add a pleat before mark A and after mark F to make the outer edges of the 1^st and 3^rd pockets expand. For this, I will need to add 1.5 inches for the pleat and ¾ inches to leave space between that first pleat and the outer edges of the lining piece.

My final slip pocket dimensions are: 25.75 inches wide x 8 inches high. You should cut out (2) lining fabric and (2) fusible woven interfacing pieces. Fuse the interfacing to the wrong side of both fabric pieces.

Sewing your slip pocket

Step 1: Place your slip pocket pieces so they are right sides together, pin/clip along the top and bottom edges then sew together, making sure to backstitch. Your slip pocket will now be in a long tube.

Step 2: Turn your slip pocket right side out and press the seam nice and flat along the top and bottom edges. Topstitch the top edge with 1/8” seam allowance.

Step 3: The marks from Figure 1 need to be transferred to the top and bottom edges of your slip pocket. You can use either a fabric pen or use pins like I have.

Step 4: At each mark designated by the letters A to F, you must fold the slip pocket so it is wrong sides together and press to create a crease from the top, to the bottom edge. Make sure all creases are folded in the same direction, with wrong sides together.

Step 5: At each of the folded edges, stitch the fold in place with a very small seam allowance, less than 1/8”, to hold it in place. You can switch out your presser foot, or use one of the markings in your needle plate to help guide the fabric. I have the Janome Ultra Glide foot on my Janome HD-9. It’s a great presser foot to use for sticky “fabrics” like vinyl, cork and leather.

Step 6: Your slip pocket should look like the photo above once all folded edges have been topstitched. Make sure to leave the pins or marks in between as they indicate where your slip pockets will be divided.

Step 7: Now we will pleat the bottom of the slip pocket. Start by bringing the folded edge at mark A towards the remaining mark on the left (shown with a pin in the photo above). Use a clip or pin to hold in place. Repeat this same step to pleat at the opposite end except in the opposite direction by bringing the folded edge at mark E towards the mark on the right and use a clip or pin to hold in place.

Step 8: For the folded edges at marks B and C, they must be folded in towards the center mark indicated by the pin in the photos above.  Use clips to hold them in place. Repeat this for marks D and E.

Step 9: Your slip pocket should now look like the photo above. Take your lining piece and place it on your work surface, then place the slip pocket over top both right sides facing up.

Step 10: Start by pinning or clipping the bottom left and right corners to the edges of your lining piece. I recommend placing the pocket at least 1” from the bottom corner of your lining. Then pin or clip the top corner of your slip pocket to the lining piece along both edges. (Note: only the right edge of the lining and slip pocket are shown in the photo above).

Step 11: Maintaining the same distance between the bottom edge of the slip pocket and the bottom of the lining, pin or clip the remaining bottom edge of your slip pocket. Pin the top edge of your slip pocket to the lining at the marks we made in step 3.

Step 12: Sew the bottom edge of the pocket to the lining piece, making sure to backstitch back and forth a few times at every pleat to secure it. Then baste the left and right sides of the slip pocket to your lining using a long basting stitch and ¼” seam allowance. This will allow you to remove all of the clips except for the pins marking the separation of the pockets.

Step 13: The last step to creating our pockets is to sew the seams separating our pockets. Start by sewing from the bottom to the top edge of the slip pocket at the first set of marks on the left, before pleat A and then the set of marks on the right, after pleat E. Make sure to backstitch at the top edge of the slip pocket to secure your pocket’s opening.

Step 14: When sewing the marks between pleats B and C, it is easier to start at the top edge of your slip pocket, backstitch, then sew down to the bottom edge, between the pleats and backstitch again. Repeat this step for the marks between pleats D and E.  

You should now have 3 separate slip pockets!

Happy Sewing!
Celine