What a flap pillowcase is and why you might choose it

A flap pillowcase is a standard pillowcase with an extra fold of fabric that overlaps the opening, like an envelope. Instead of the pillow showing at the mouth of the case, the flap covers it. The flap serves two purposes: it keeps the pillow from sliding out during the night, and it hides the seam where the opening closes.

The flap adds about 15 minutes to the sewing time compared to a basic pillowcase, and it uses roughly the same amount of fabric. If you have already sewn a flat pillowcase, you have the skills to make one with a flap.

Key Takeaways

  • A flap pillowcase requires one piece of fabric folded in half, with the flap created by extending one end before you sew the sides.
  • You cut a rectangle roughly 21 inches wide by 33 inches long for a standard pillow, then fold it so the flap naturally overlaps the opening.
  • The flap is sewn as part of the side seams, not added separately, so you sew only three sides instead of four.
  • You turn the case right-side out through the opening left by the flap, so no hand-stitching is needed to close it.

Fabric size and how to measure for your pillow

Start by measuring your pillow. A standard bed pillow is usually 20 inches wide by 26 inches long. Measure yours to be sure, because decorative pillows vary.

For a pillowcase with a flap, cut a rectangle of fabric that is twice the length of your pillow plus 8 inches, and the width of your pillow plus 1 inch for seam allowance. For a 20-by-26 pillow, that means cutting a rectangle 21 inches wide by 60 inches long. The extra 8 inches becomes the flap.

If you are using a patterned fabric and want the pattern to run the same direction on both sides of the finished case, buy fabric that is at least 60 inches long. If the pattern direction does not matter, 45-inch-wide fabric is enough.

Cutting and preparing the fabric

Cut your rectangle to size using a rotary cutter and ruler, or mark the lines with tailor's chalk and cut with scissors. Make sure the corners are square — use a quilting square to check them.

Lay the rectangle flat with the right side (the side you want to show) facing down. This is the side that will be on the outside of the finished pillowcase. If your fabric has a nap or a direction you want to follow, make sure it runs the way you want it to before you start sewing.

Press the fabric with an iron to remove wrinkles. Wrinkles make it harder to fold evenly and sew straight lines.

Folding the fabric and marking the flap

Fold the rectangle in half lengthwise, with the right side still facing inward. The fold should be on one of the long sides. You now have a double layer that is roughly 21 inches wide by 30 inches long.

The flap is the part that sticks out beyond the fold. On the open end (the end opposite the fold), measure 4 inches from the edge and mark a line across the width of the fabric with tailor's chalk or a fabric pen. This line shows where the flap begins. The 4-inch flap will fold over the opening once the case is turned right-side out.

Pin the two layers together along the sides and the end without the flap, leaving the flap area unpinned for now.

Sewing the three sides

Set your sewing machine to a straight stitch with a stitch length of 2.5 to 3 millimeters. Use a thread color that matches your fabric, or use neutral gray or tan if you are mixing colors.

Start at the fold and sew down one long side, using a half-inch seam allowance. Sew to the end of the fabric, then turn the corner and sew across the end (the end without the flap). When you reach the other long side, sew back up to the fold. You have now sewn three sides in a U shape, leaving the flap end open.

Backstitch at the beginning and end of each seam to lock the thread. Trim the thread tails.

Clip the corners diagonally, cutting away the fabric at a 45-degree angle about a quarter-inch from the corner seam. This reduces bulk when you turn the case right-side out and makes the corners lie flat.

Turning the case right-side out and finishing

Reach into the opening where the flap is and grab the fold of fabric at the opposite end. Pull gently until the entire case turns right-side out through the flap opening. The flap will naturally fold over the opening as you do this.

Use a point turner or the blunt end of a chopstick to push the corners out from the inside so they are sharp and square. Press the entire case with an iron, paying special attention to the edges and the flap fold.

The flap opening does not need to be sewn shut. The weight of the pillow inside and the natural fold of the fabric will keep it closed. If you want extra security, you can topstitch along the fold of the flap — sew a line of stitching about a quarter-inch from the fold, which will hold the flap in place and add a decorative detail.

Troubleshooting common problems

If the flap is too loose and does not stay folded, your flap measurement was too small. For the next case, cut 5 or 6 inches instead of 4. If the flap is too tight and pulls at the opening, cut 3 inches next time.

If the corners are rounded instead of sharp, you did not clip them deeply enough before turning. Next time, cut closer to the seam (but not into it). If the case is twisted or bunched after turning, you may have pulled too hard — turn it more slowly and adjust the fabric as it comes through the opening.

If the seams are wavy, your fabric was not pinned tightly enough or you were not feeding it evenly under the presser foot. Slow down and use both hands to guide the fabric, keeping it flat against the bed of the machine.

Frequently Asked Questions

Can I use a flap pillowcase with a standard pillow insert?

Yes. The flap is designed to work with any pillow that fits the width and length of the case. Standard bed pillows, body pillows, and decorative square pillows all work. The flap straightforward folds over the opening and stays in place from the weight of the pillow.

Do I need to sew the flap opening closed by hand?

No. The flap opening is left unsealed intentionally. The fold of the flap and the weight of the pillow keep it closed during use. If you want a more finished look, you can topstitch along the fold, but it is not necessary for function.

What seam allowance should I use?

A half-inch seam allowance is standard and works well for pillowcases. If you are new to sewing, mark your seam allowance with a piece of tape on the bed of your machine so you can follow it without measuring each time.

Can I make a flap pillowcase from a single layer of fabric instead of folding?

You can, but it requires sewing four sides and hand-stitching the opening closed, which takes longer. Folding the fabric in half is faster and gives you a finished edge at the fold, so you have fewer seams to manage.

How much fabric do I waste with this method?

Almost none. You cut one rectangle and use the entire piece. There are no scraps unless you trim the seam allowances, and even those are small.