1. Prepare Your Fabric Edges

• Determine your finished hem or border width (common widths: 1/4 in, 1/2 in, 1 in, or 2 in depending on project).
• Press under the raw edge on both sides meeting at the corner by the hem width measurement.
• Press under again by the same measurement to create a double-fold hem (or single fold if working with bindings or finished edges).
• Unfold the fabric completely so you can see the pressed crease lines.

2. Mark the Miter Diagonal

• Refold each edge once (first fold only) so the two creases meet at the corner, forming an L-shape.
• Lay the fabric wrong side up with the corner toward you.
• Identify where the two inner fold lines intersect at the corner—this is your starting point.
• Using a ruler and marking tool, draw a diagonal line from the intersection point to the outer corner point at a 45-degree angle.
• The diagonal line should bisect the corner square perfectly.

3. Stitch the Miter

• Fold the fabric right sides together along the diagonal line you just marked, aligning the pressed creases on both edges precisely.
• Pin or clip in place to secure.
• Stitch directly on the marked diagonal line from the inner intersection to the outer corner point, backstitching at both ends.
• Use a standard stitch length (2.0–2.5 mm).

4. Trim and Grade the Corner

• Trim the seam allowance to approximately 1/4 in from the stitching line.
• Clip the corner point at a diagonal, removing excess bulk but staying about 1/8 in away from the stitching to prevent fraying.
• If working with thick fabric, grade the seam allowances by trimming one layer slightly narrower than the other to reduce bulk.

5. Press the Miter Seam

• Press the miter seam open using the tip of your iron to set the stitches and flatten the allowances.
• Work carefully to avoid stretching the bias edge.

6. Turn and Shape the Corner

• Turn the corner right side out, gently pulling the fabric through.
• Use a point turner, chopstick, or blunt tool to carefully push out the corner point from the inside—work gently to avoid poking through.
• Press the mitered corner flat, aligning the folded edges perfectly along both sides.

7. Complete the Hem

• Refold the hem along the original pressed creases to encase the raw edges.
• Pin or clip the hem in place around the entire project, paying special attention to the mitered corners.
• Edgestitch or topstitch the hem close to the inner folded edge (typically 1/8 in from the fold), pivoting at each mitered corner.
• Backstitch at the beginning and end, or lock stitches.

8. Press the Finished Corner

• Give the completed mitered corner a final press from both the right and wrong sides.
• Use steam if appropriate for your fabric to set the miter crisply.
• Admire your sharp, professional 45-degree corner.

9. Troubleshooting Common Issues

• Corner not sharp: Ensure you trimmed close enough to the stitching and used a point turner; re-press with steam.
• Puckered miter: Check that both hem widths are identical and fabric edges were aligned precisely before stitching.
• Lumpy corner: Trim more bulk from the seam allowance and corner point; grade if necessary.
• Diagonal line off-angle: Use a quilting ruler to mark an exact 45-degree angle from the fold intersection to the outer point.
• Raw edges showing: Ensure the second fold fully encases the first fold and raw edge; adjust fold widths if needed.