How to Add a Zipper and Line a Knit Bag

There’s a special kind of satisfaction that comes with finishing a knit bag. You’ve put in the hours, chosen beautiful yarn, and now you’re holding something both handmade and functional. But if you’ve ever dropped your phone into an unlined knit bag only to watch it slowly work its way through the fabric and onto the floor, you know exactly why lining and a zipper matter so much. A fabric lining keeps your belongings secure, gives the bag structure, and hides the inside of your work for a clean, professional look. A zipper adds security and polish that transforms your handmade bag from a craft project into something you’d genuinely see in a boutique.

This tutorial walks you through the entire process of adding a zipper and a fabric lining to a knit bag, step by step. Whether you’re a beginner to sewing or an experienced crafter who’s never sewn a lining before, you’ll find everything you need here to get a clean, beautiful finish.

What You’ll Need

Before you begin, gather your supplies. Having everything on hand before you sit down saves a lot of frustration mid-project.

For the lining, you’ll want a woven fabric — cotton quilting fabric, canvas, linen, or even an old pillowcase all work well. Avoid stretchy fabrics like jersey, which won’t give the bag the structure you’re after. You’ll need enough yardage to cut two pieces that match the body of your bag, plus a little extra for seam allowances. If your bag has a gusset (a flat bottom panel), cut a matching piece for that too.

For the zipper, choose a zipper that’s slightly shorter than the width of your bag’s opening. If your bag is 12 inches wide at the top, a 10- or 11-inch zipper works beautifully. You can use a regular dress zipper, a nylon coil zipper, or a bag-specific zipper — whatever color and style coordinates with your yarn. Zipper tape is forgiving and easy to sew, so don’t be intimidated.

Here’s a full supply list to have ready:

Woven fabric for the lining (enough to cut your bag’s panels plus seam allowances), a zipper in the appropriate length, a sewing machine or hand-sewing needle and thread, fabric scissors or a rotary cutter and mat, straight pins or binding clips (clips are especially useful on knit fabric since pins can distort it), a zipper foot for your sewing machine, an iron and ironing board, fabric marking chalk or a water-soluble pen, and a tape measure or ruler.

Optional but helpful: fusible interfacing, which you can iron onto your lining fabric for extra structure, and seam binding or bias tape to finish the inside seams neatly.

Step 1: Measure Your Knit Bag

Start by measuring your finished knit bag carefully. Lay it flat on a table and measure the width across the top opening, the depth from top to bottom, and the depth of the gusset or flat bottom if your bag has one.

Write everything down. You’re going to use these measurements to cut your lining fabric, and precision here saves headaches later. Keep in mind that knit fabric has give, so if your bag stretches when you measure it, hold it in its natural resting shape rather than pulling it taut.

Add half an inch to one inch to each measurement for your seam allowances. Most sewists use a half-inch seam allowance for lining work, but if you’re new to sewing, a full inch gives you more room for error and is easy to trim down later.

Step 2: Cut the Lining Fabric

Using your measurements, mark and cut your lining pieces from your chosen fabric. For a simple tote-style knit bag, you’ll typically cut two identical rectangles — one for the front panel and one for the back. If your bag has a separate flat bottom, cut a rectangle for that as well.

If you’re using interfacing, cut matching pieces and fuse them to the wrong side of your lining fabric now, before you do any sewing. Fusible interfacing is ironed on with a pressing cloth, and it stiffens the fabric just enough to give your bag wonderful body. Follow the package directions for heat setting, since different interfacing weights require different iron temperatures.

Once your pieces are cut and interfaced if desired, press them with a hot iron. Smooth, pressed fabric is far easier to sew accurately than fabric with wrinkles or folds.

Step 3: Sew the Lining Together

Place your two main lining panels right sides together — meaning the printed or “nice” sides of the fabric face each other and you’re looking at the wrong side. Pin or clip the side seams and the bottom seam, leaving the top open.

Sew along the side seams and the bottom seam using your chosen seam allowance. If your bag has a gusset, sew the bottom panel to the two main panels now, matching corners carefully.

To create a flat bottom without a separate gusset panel, you can box the corners of your lining. After sewing the side and bottom seams, pinch each bottom corner so the bottom seam and side seam align on top of each other, forming a triangle. Measure and mark a line across the triangle at a distance that matches your desired gusset width — typically two to three inches — and sew across that line. Trim the excess triangle fabric to about half an inch from your stitching. When you turn the bag, those corners will pop out into a nice flat bottom.

Press your seams open or to one side, and press the top edge of the lining down by the width of your seam allowance so it folds to the inside. This folded edge is what you’ll eventually stitch to attach the lining to the zipper tape. Set the lining aside for now.

Step 4: Prepare the Zipper

Take your zipper and place it face up on your work surface. If your zipper is longer than the opening of your bag, you can shorten it easily. Simply mark the length you need with a fabric marker, then sew a few tight zigzag stitches across the zipper teeth at your mark using your sewing machine, creating a new zipper stop. Trim the excess zipper tape about an inch beyond your new stop.

Now look at both ends of the zipper tape. The raw ends — the parts that won’t be hidden by a zipper pull or stop — need to be folded under or tucked away so they don’t fray or look unfinished. Fold each end of the zipper tape back on itself at a 45-degree angle and press with your iron, or simply fold the ends straight back and press them flat. A few hand stitches to secure the folds are helpful.

Step 5: Attach the Zipper to the Bag Opening

This is the step that intimidates most knitters, but it’s more straightforward than it looks. The key is going slowly and using plenty of pins or clips.

Lay your finished knit bag flat on your work surface with the right side facing up. Open the zipper halfway so the pull is out of the way as you sew.

Place the zipper face down along the top edge of one side of the bag’s opening, aligning the zipper tape with the very top edge of the knit fabric. The zipper teeth should be pointing toward the interior of the bag. Pin or clip the zipper in place every inch or so.

Using your zipper foot — a narrow presser foot that lets you sew right up close to the zipper teeth — stitch the zipper tape to the knit bag along the top edge. Go slowly and keep your stitching close to the teeth but not on them. Sew from one end of the zipper to the other.

Fold the zipper up and over to the right side of the bag and topstitch along the edge of the bag if you like. Topstitching flattens the seam and gives a crisp, neat look.

Repeat this process on the other side of the bag’s opening, attaching the remaining zipper tape to the opposite top edge. Make sure you’re not twisting the zipper as you do this — open and close it gently after pinning to confirm everything lines up before you sew.

Step 6: Attach the Lining

Now take your prepared lining, which should be sewn, pressed, and have its top edge folded under. Slide the lining into the bag with the wrong sides of the lining and the bag facing each other — essentially slipping the lining inside the bag so the nice side of the lining faces the interior of the bag.

Match the side seams of the lining to the side seams of the knit bag as best you can, and use pins or clips to hold everything in place around the top opening.

The folded top edge of your lining should sit just below the zipper teeth, covering the raw zipper tape and the seam where you attached the zipper. Adjust until you’re satisfied with the placement, then pin or clip the lining folded edge all the way around the opening.

Using a needle and thread, slipstitch the lining to the zipper tape and the bag opening by hand. Slipstitching is a nearly invisible stitch made by catching a tiny bit of the lining fabric, then a tiny bit of the zipper tape or bag fabric, alternating as you work around the opening. Take your time and pull each stitch just snug — not tight enough to pucker — and you’ll end up with a finish that looks as if it came out of a factory.

Alternatively, if your bag’s knit fabric is stable enough not to stretch under the presser foot, you can machine stitch the lining in place using your zipper foot. Stitch just below the zipper teeth, catching the lining’s folded edge and the zipper tape in a single line of stitching.

Step 7: Close the Lining Bottom (If Needed)

If you left a gap in the lining’s bottom seam to help turn the bag right side out during construction, or if you find the bottom of the lining is loose, slipstitch that closed now by hand. Fold the raw edges under and whipstitch across the gap with small, even stitches.

Tips for a Professional Finish

The difference between a bag that looks handmade and one that looks professionally crafted usually comes down to a few small details.

Press everything at every stage. Ironing your seams flat, pressing the top edge of the lining before stitching, and pressing the zipper tape before attaching it all contribute to a tidy result. If you’re worried about pressing knit fabric directly (some wool or acrylic yarns can’t take direct heat), use a pressing cloth or steam lightly without touching the iron to the knits.

Match your thread to your lining fabric, not your yarn, for the hand stitching that attaches the lining. This makes the stitching nearly invisible from the inside.

If your bag is made from a particularly loose or open knit, consider cutting your lining pieces slightly smaller than the bag measurements — about a quarter inch all around. A lining that’s a hair smaller than the bag gives the whole thing a smoother shape and keeps the lining from sagging or billowing inside.

For bags with handles that are also knit or crocheted, reinforce the handle attachment points on the inside of the lining with a small square of sturdy fabric hand-stitched over each point. This is especially important if you plan to carry anything heavy.

Choosing the Right Lining Fabric

The lining fabric you choose affects both the look and the function of the finished bag. Here are a few popular options and what makes each one useful.

Cotton quilting fabric is widely available, comes in thousands of prints and colors, and is easy to cut and sew. It’s lightweight enough not to add bulk but opaque enough to fully hide the inside of the bag. This is probably the easiest fabric to work with if you’re new to lining bags.

Canvas or home décor fabric gives bags wonderful structure and durability. If you’ve knit a large market tote or a beach bag, a canvas lining turns it into something that will hold heavy items without sagging. The trade-off is that canvas is thicker and can be harder to hand-stitch neatly.

Linen has a beautiful texture and wears extremely well. It’s slightly stiffer than quilting cotton but more relaxed than canvas, making it a great middle-ground option for bags of any size.

Laminated or coated cotton (sometimes called oil cloth) makes a water-resistant lining that’s ideal for bags that might carry wet swimsuits, water bottles, or groceries. You can’t pin laminated fabric without leaving permanent holes, so use clips instead, and don’t iron it directly.

Common Mistakes and How to Avoid Them

One of the most common errors is cutting the lining the same size as the bag’s outer measurements without accounting for the thickness of the bag fabric itself. A thick, squishy knit bag takes up space, and a lining cut to the exact outer dimensions may end up too large and loose. Measure the interior of the bag if you can, or cut the lining slightly smaller and adjust as needed.

Another frequent issue is a zipper that puckers or waves after being sewn. This usually happens when the knit fabric stretches as it passes under the presser foot. Combat this by supporting the weight of the bag with your hand as you sew, keeping tension even, and sewing slowly. You can also baste the zipper in place by hand first, which lets you check the lay of everything before committing to machine stitching.

Finally, some people struggle with the zipper pull getting in the way while sewing. Remember that you can open and close the zipper at any point during construction. When you’re sewing and the pull approaches the presser foot, stop with the needle down, lift the foot, move the pull out of the way, lower the foot, and continue. This keeps your stitching line straight without having to sew around the bump of the pull.

Finishing Touches

Once your zipper is in and your lining is secured, give the entire bag a final gentle press, using a pressing cloth over the knit sections. Turn the bag inside out briefly to inspect your lining stitches, then flip it back and open and close the zipper a few times to make sure everything moves smoothly and nothing is catching.

If you want, you can add a small interior pocket to the lining before you sew it into the bag. Simply cut a rectangle of lining fabric, fold it in half right sides together, sew the sides, turn it right side out, and topstitch it to one lining panel before assembling the lining. A little pocket for your phone or keys is a practical addition that takes only a few extra minutes.

Adding a zipper and lining to a knit bag is genuinely one of those finishing skills that elevates everything you make afterward. Once you’ve done it once, you’ll wonder why you ever skipped it. The bag holds its shape, your belongings stay where you put them, and every time someone asks where you got it, you’ll get to say you made it yourself.