A mitered corner is a tidy, diagonal seam that joins two folded edges at a corner, creating a clean, flat finish with minimal bulk. They are more commonly seen in quilting and home decor than garment sewing, but they do occasionally pop up in bodice hems, sleeve hems, or pockets.
Personally, I find mitered corners mesmerizing — there’s something so satisfying about that crisp, clean angle. Not only does it give a beautifully professional finish, but it also reduces bulk where multiple folds would otherwise stack up.
Before we dive into the tutorial, let’s quickly break down how double-fold mitering works conceptually. Once you understand the logic behind it, you won’t have to second-guess which fold goes first — no more fumbling!
And one more thing... this post is also available in video if you prefer:
How Mitering Works
Mitering double-fold corners used to confuse me — all those overlapping folds made it hard to tell what went where. Then one day it clicked: the first fold is just a seam finish. It’s not part of the structure; it’s part of the fabric now.
That shift in thinking made everything easier. When planning the folds and stitch lines, I treat that first fold as if it’s already permanently glued down — the fabric is essentially pre-finished and fray-free.
To figure out where to stitch, I like to simulate the folds with a piece of paper. Fold it twice on both sides to mimic the double-fold hem, then snip into the corner where the mitering stitch line would go. Unfold it once, and voilà — you can see exactly where the seam should be. Sewing it on fabric is the same idea, just with added seam allowance.
The length of the second fold doesn’t affect the technique — you can use equal or unequal folds, and the miter will still work beautifully. Equal lengths will give you a classic 45-degree mitered seam, but uneven folds are just as clean and satisfying. In the example below, I’ll demonstrate the technique using unequal folds: the hem is folded up ⅜" (1 cm), then 1" (2.5 cm), and the side edge is folded in ⅜" (1 cm), then ⅝" (1.5 cm).
How To Sew
Fold the hem up by ⅜" (1 cm), then again by 1" (2.5 cm). Fold the side edge in by ⅜" (1 cm), then ⅝" (1.5 cm). Press all folds to crease them well. Then, open just the second fold on both the hem and side — keep the first fold closed for the rest of the steps.
From the corner of the once-folded fabric, measure out twice the depth of each second fold — in our case, 2" (5 cm) up, and 1¼" (3 cm) to the left. Mark those two points and draw a line connecting them; this will be our stitch line.
Fold the corner right sides together, forming a triangular shape so that the marked stitch line overlaps itself. Pin if needed.
Sew along the stitch line, starting from the folded edges with a few backstitches. Stop about 1/16" (1-2 mm) before the end and backstitch again. Avoid sewing all the way to the end — backstitches there can create extra bulk when the corner is turned out.
Cut ⅜" (1 cm) away from the stitch line to leave a seam allowance.
Press this seam open. At the very tip, pull it open to form a neat little right triangle.
Turn the corner right side out, and press until it lays flat and crisp.
Finally, topstitch down the folds, pivoting 90 degrees at the corner.
And that’s it — a clean, crisp mitered corner! Once you get the hang of this technique, it’s surprisingly straightforward, satisfying, and addictive. You’ll start spotting all sorts of places where a tidy little mitered corner would be just the thing.
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