The square pillow – it’s a decorating staple and a great way to freshen up a room. You pick your favorite fabric, measure carefully, and cut two perfect squares. You sew the seams, pivoting at each corner with precision, and insert the pillow form. You set the finished pillow on the sofa, and… Hey! That pillow doesn’t look square! Instead of crisp straight edges, the sides curve in toward the center and the corners are floppy. Use this quick pro tip to learn how a slight curve can create a better square.

It might seem like a geometric rule-breaker, but one trick to keeping a square pillow square is tapering the corners rather than sticking with a classic 90˚ angle. The grouping of photos above shows the comparison of a standard angle to a tapered angle on two identical 18″ pillows from a number of different perspectives. Clockwise: tapered on top, standard on bottom; standard on the left, tapered on the right; tapered on the right, standard on the left; standard at the right, tapered at the left – and below: a close-up of tapered on top, standard on bottom.

Must you do this every time? Nope. We’re never ones to make you do anything. For lightweight cotton pillows with cushy inserts, especially in smaller sizes, standard square corners can be just fine. You can use the technique any time, but it’s particularly effective with heavier décor weight fabrics or when using thick trims. We show both piping and fringe below.

The main advantage of the tapered corner technique is how the slightly wider angle at each corner allows thicker fabrics, piping, and trim to turn into the corners more easily. The end result is a smoother corner, without that little tuck that so often happens with a true 90° angle.

Our Luminous Jewel Box Pillow Pair in Silk Patchwork introduced this simple technique, but we’ve expanded it here with full, step-by-step instructions.

The samples shown are 18″ x 18″ squares of fabric. The formula, dividing the sides into thirds, works for any size square or rectangle. Just remember to treat each side separately.

1. Cut two squares for each pillow.
2. Divide one side of one square into thirds. Place a mark at each third. In our sample, this meant we had marks at 6″ and 12″ along the raw side edge.
   
3. Place an additional mark ½” in from each corner.
4. Rotate the square 90° and mark the second side. Repeat for the remaining two sides until you have two dividing marks along each side and a ½” box at each corner. Repeat for the remaining square.
   
   NOTE: As mentioned, this technique works well for all sizes of square pillows. When working with larger pillows, such as a 24″ or 28″ square, increase the corner mark from ½” to ¾” from the edge. When working with smaller pillows such as a 10″ – 12″ accent pillow, reduce the corner mark from ½” to ¼”. The seam allowance stays at ½”, only the size of the “corner box” changes.
5. Using a ruler and a fabric marking pen, connect your marks at each corner, forming a sloping “X”. You are drawing a line from the side dividing mark into the corner mark as shown below. Notice how this changes the angle of the corner from 90° to an obtuse angle.
   
6. Trim along the marked lines.
   
7. Place the two adjusted squares right sides together. The raw edges of both layers should be flush all around.
8. Using a ½” seam allowance, stitch the layers together, following the newly cut, tapered raw edge at each corner. You are still pivoting at each corner.
   
   NOTE: This technique works with either a simple sewn pillow, where you leave an opening in the seam along one side for turning the pillow right side out, as well as for an envelope back pillow. For a buttoned closure or overlapped closure, there is, of course, no need to leave an opening in the seam for turning, plus you are tapering just the outside corners of your two back pieces; the inner corners become part of the overlapping hems.
9. Trim each corner diagonally.
   
10. With the corner at the new wider angle, when turned right side out, the trimmed seam allowances will fit smoothly into the corner, resulting in a crisp angle.
    

Working with trim

1. To add piping to the pillow, baste the piping to the pillow front, matching the edge of the piping’s insertion strip to the raw edge of the adjusted fabric square. Clip into the seam allowance of the piping at each corner.
   
2. Pivot at this corner clip, with the needle in the down position.
   
3. Align the piping with the opposite side of the adjusted square corner and continue sewing. Repeat at each corner.
   
4. Join the ends of the piping, sandwich front to back, and complete as normal. Your final seam can simply follow the previous line of machine basting.
   
5. Fringe can be applied in a very similar manner. Match the edge of the fringe header to the raw edge of the adjusted fabric square. Clip at the corners and pivot, taking care to snip up to but not through the last line of stitching on the header.
   
6. When using fringe, notice how the wider angle at the corner allows the fringe to fan around the corner instead of splitting.
   

When your pillow is complete, it’s time to insert the pillow form. Here again, the wider angle at the corners works to your advantage. The stiff corners of the pillow form fit more easily into each corner, which helps to eliminate those floppy “dog ears” you sometimes see at the corners of a finished pillow.

Go forth and cut a few corners!