How to Sew Mitered Corners of Unequal Lengths

Did you know that Chanel’s iconic boucle jackets are finished with mitered corners?

If it’s good enough for Coco, it’s good enough for me — and you!

In this article, you will learn how to make a SPECIAL kind of mitered corner — a corner in which the folds that meet are different lengths.

But, what does that mean? Here’s an example that will clear things up:

The center front edge of a skirt might be folded to the wrong side 1 inch, and the skirt hem might be folded up 2 inches. The overlap created by the folds would be 1 by 2 inches. (In case you’re not picking up what I’m throwing down, 1 inch and 2 inches are the unequal lengths.)

I learned how to sew mitered corners of unequal lengths because I wanted an elevated hem finish on this rainbow flannel dress (a spin on the Darling Ranges from Megan Nielsen). To be honest, I’m surprised Chanel’s atelier hasn’t come calling (ha!).

Let’s get into the glories of how to hem uneven mitered corners. After you master this technique, maybe Chanel will be hot for you, too.

This post features affiliate links chosen for you. If you click through and make a purchase, I may receive a commission at no additional cost to you. Affiliate advertising is the main way I earn income from Sie Macht, and I thank you for your support! 💙

What is a Mitered Corner?

With a mitered corner, layers of fabric join together (with a seam) instead of overlapping and creating bulk. You can miter corners of any angle and any length.

Check out these paper examples; fabric works the SAME WAY (and, TBH, it’s kinda fun to make these goofy little shapes):

a.) Acute angle, equal lengths

b.) Acute angle, unequal lengths

c.) Right angle, unequal lengths

d.) Right angle, equal lengths

e.) Obtuse angle, equal lengths

f.) Obtuse angle, unequal lengths

RELATED: Rainbow Darling Ranges Dress: A Flannel Encore

When to Use a Mitered Corner

Mitered corners are perfect for any spot where the fabric takes a turn, sharp or wide.

The following use cases are practically made for mitered corners:

• Corner of a cardigan or jacket

• Split hem

• Corner of a skirt hem

• Jacket vent

You can sew a mitered corner in any fabric, woven or knit. If the pattern calls for a corner, you can miter it!

For me, there are two main reasons to sew a mitered corner:

1. They look professional. It’s a technique that DEFINITELY levels up DIY fashion from “homemade” to “handmade.”

2. They reduce the bulk of corners where two folded edges collide. At the very least with two folded edges, you end up with four layers of fabric.

Something I’ve learned over many years of sewing and reading about sewing and watching videos about sewing (I’m a LITTLE obsessed with sewing…) is that you should reduce bulk when you can.

RELATED: Sewing Corners on Me-Made Garments Like a Pro

What You Need to Sew a Perfect Corner

To sew mitered corners, you need the following sewing supplies:

• Chalk or other marking tool
• Iron
• Ruler
• Scissors or rotary cutter
• Thread
• Point turner
• Sewing machine
• Pins

I suggest using scrap fabric to practice this technique before applying it to your real-deal project. You also can practice with paper (for a more origami vibe, if that appeals to you).

How to Sew Mitered Corners of Unequal Lengths

This technique is adapted from “Sewing Secrets from the Fashion Industry,” one of my favorite sewing books.

If your two folded edges are unequal in length, keep reading for how to miter them like a boss.

1.) Finish the raw edges of the fabric that will make up the mitered corner. This could be giving them a tiny fold (¼ inch) over, zig-zag stitch, serging, or pinking. Sewist’s choice!

2.) Place the fabric wrong side up. Fold the finished edges in your desired order to the wrong side. For example, if I were making the aforementioned skirt, I’d first make the center-front fold, and then I’d fold up the hem.

3.) Give this non-mitered corner (don’t worry about goofy edges sticking out at this point) a gentle press with your iron. We’re making a memory of the major folds.

4.) Turn the fabric over and place it right side up. Unfold the corner. You should have pronounced fold lines, thanks to the gentle iron press.

5.) Fold the finished edges to the right side in reverse folding order. So, continuing with the skirt example, here I would fold up the hem first and then fold over the center front.

6.) With your marking tool, draw a diagonal line from the bottom outer corner of the intersecting folds to the top inner corner. Overdraw a little bit (1/16 to 1/8 inch) onto the wrong side of the fabric.

7.) Fold back the top fold along the diagonal line. Finger press the diagonal fold. You are peeling away the top fold to look at the bottom fold.

8.) Run your marking tool along the edge of the diagonal crease, drawing a diagonal line from the bottom outer corner to the top inner corner (the overdrawing helps you find the endpoint of this line). Now there should be a diagonal line on the top fold and a diagonal line on the bottom fold. In the case of the skirt example, there’s a line on the center front and the same line on the hem.

9.) Unfold the corner, wrong side up, and look at the two diagonal lines. Using a straight edge and marking tool, connect the lines from finished edge to finished edge. (Isn’t it wild how they come together? This feels like magic!) This line is your stitching line for creating the miter.

10.) Let’s create a seam allowance. Using a ruler, draw a line that’s:

• ¼ inch from the stitching line

• Closer to the outer corner

11.) Cut off the outer corner on the seam allowance line. (Cutting away fabric may scare you, but it’s the right thing to do!)

12.) Right sides together, fold the stitching line in half. When you fold the line, the upper part of the line and the lower part of the line should exactly stack on top of each other. Stick a pin through the stitching line, from one side of the fabric to the other, to confirm alignment.

13.) Sew along the stitching line to create the corner seam; backstitch at both ends.

14.) On the wrong side, open the mitered seam and press. Trim the corner to remove bulk.

15.) Turn the mitered corner right side out. (A point turner here is helpful to create a sharp point.) Gently press on the right side.

16.) Sew the unequal hems in place! And ya done. Well done!

Final Thoughts About Sewing Mitered Corners

This is one of those sewing techniques that, once you’ve mastered it, you look for opportunities to put it into practice. Sewing mitered corners makes you feel like a professional; they’re tidy and take a bit of brainwork to get right.

The No. 1 thing to remember when sewing mitered corners, especially when edges are uneven, is to PRACTICE FIRST. It’s better to do a run-through with paper or scrap fabric than to cut off the wrong part of your corner.

IN FACT…

DUN-DUN-DUUUUN…

That’s exactly what I did with one corner of my rainbow flannel dress! I *thought* I had a handle on what I needed to trim away from the seam allowance. But, because I had my corner folded incorrectly, I cut away too much/the wrong area of fabric. (I think I failed to reverse my folding order when folding to the right side.)

As you can see from the photos, I came back from this boneheaded move and sewed a lovely unequal miter in spite of it. (If you’d like to see how I fixed the cut-off fabric corner, please LMK in the comments!)

Anyhoo, when I tell you to practice your miter first, I speak from experience.

Over to you: Have you sewed a mitered corner? How did it go? Where did you get your instruction? If you haven’t tried this technique yet, why not? Please share with your sewing friends!