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No More Gaping: 3 Techniques for Perfect Armholes on Knits

Sleeveless knits like Moneta or Wren can get a little tricky. If you’ve ever experienced gaping around the armholes on sleeveless garments, read on for several fixes you can use.

Why do knits gape?

First, let’s talk about the why.

On a woven garment, bust darts (or sometimes princess seams) allow for the fullness of the bust. Essentially, they create a cupped shape around the bust area. That means there’s extra room at the apex, but not the armhole or side seams.


Here’s an example: The Seamwork Adelaide. The dart helps cup the bust.

Knits typically do not have bust darts. Instead, they rely on the cut of the outer edges along with the stretch of the fabric itself to accommodate the bust.

This means that a lot rides on your fabric and how it responds to stretch and handling while it’s sewn. For fitted knit dresses without sleeves, if your fabric doesn’t have excellent recovery, or if it gets a bit stretched out when being sewn, you can get extra fullness around the arm opening.


Here’s the Wren in a cotton French terry without a lot of recovery. You can see that it’s gaping a bit at the curve of the armhole.

The larger your bust is, the more you might notice this problem with sleeveless fitted knits.

Luckily, this is easy to check, fit, and fix as you’re sewing. So let’s fix it!

Check the fit

First of all, check the fit as you’re sewing a fitted sleeveless knit garment. After you’ve sewn the shoulder and side seams, but before finishing the armholes, try it on.

Notice if you’ve got a bit of extra fabric forming a little fold that radiates from your bust apex.

Pinch it out, pin it, and measure. Now you have several options to reduce this fullness.


Option 1: Add a dart

This is the simplest way to get rid of gaping.

Pinch the fold on the wrong side of the fabric and sew into a dart, using a stretch stitch such as a narrow zigzag.



  • Really easy to do.
  • Gives a tailored fit.
  • Works great on stable knits, like ponte.


  • Changes the style lines slightly.
  • Stitches can be prone to popping.

Option 2: Add a band or binding

Usually with knits, the alternative to adding a dart is easing extra fabric in.

This is easy to do if you finish your armholes with a band or binding rather than a dart.

Measure the dart you pinched out. Mark the armhole about one inch past this.


Cut your band or binding so that it’s at least that much smaller than the armhole. For this example, the little dart I pinched out was 1 inch. I cut my band 2 inches smaller than the armhole. It turned out perfect.

When you sew on the binding (or band), ease between the underarm seam and the marking by stretching the binding to fit that area. I stretched the binding gently all around this armhole, but stretched it to the maximum around the curved area, where it needs the ease.


This will bring the armhole in to hug the underarm while still allowing for that needed fullness around the bust.

See our ultimate guide to knit edges if you want to learn how to install either a band or binding. I really like the band. This is my favorite alternate way to finish an armhole that gapes. It’s easy and turns out clean and fitted!


  • Looks very tidy.
  • Easy to do with a little practice.
  • Gives a really good, smooth fit.


  • Slightly more work than sewing a dart.

Option 3: Elastic edges

One more way to finish your armhole and prevent gaping is to use elastic.

Again, cut the elastic smaller than the armhole and ease through the area you marked around the pinched-out dart.


For this, you can use a decorative lingerie elastic, or try fold-over elastic. The important thing is to ease (stretch the elastic as you sew) around the area where you’re experiencing gaping.


  • Looks professional.
  • Highly elastic and durable.
  • Decorative elastic can add an ornamental twist.


  • Requires purchase of elastic.
  • Can change the look, especially if you can’t find elastic in an exact match.
  • Slightly more work than sewing a dart.

If you need help sewing lingerie elastic, check out our tutorial on sewing lingerie elastic 3 ways.

All three of these methods are great alternate finishes to use any time you find your knit gaping. It works for other areas like necklines too!

You can pick up patterns like Wren to try this out, and you might also like The Colette Guide to Sewing Knits if you want even more handy tips like this. Better yet, save some money and get them as a bundle with another pattern!

Sarai Mitnick


Sarai started Colette back in 2009. She believes the primary role of a business should be to help people. She loves good books, sewing with wool, her charming cats, working in her garden, and eating salsa.



October 21, 2015 #

What if you experiment with adjusting the pattern by bringing up the front of the armscye at the side seam, essentially building in a dart into the armhole? Then you could keep the clean look of the bodice’s front instead of adding anything to fix the issue.


October 21, 2015 #

The issue that can sometimes occur there is that pinching out the dart on the pattern and thereby raising the armhole will result in less fabric over the bust (because you are slashing and overlapping the pattern all the way through to the center front). If you have enough stretch and recovery to still have enough fullness in the bust, it works wonderfully. Without it, you might have a higher armhole and straining across the bust.

Eryn S.

October 22, 2015 #

Great tips! I often go for the dart, when I’m feeling a bit lazy. But, the dart and binding would be my preference to keep the style lines the closest to what was intended!


October 22, 2015 #

This tutorial on ‘gaping’ (knits) is the best you have come up with! Excellent.


October 22, 2015 #

Great information. Thank you so much!


October 22, 2015 #

In method three, did you mean “stretch the fabric as you sew” or “stretch the elastic as you sew?


October 22, 2015 #

Good catch, you’re right. Fixed. :)

Rebecca Pelletier

October 23, 2015 #

Awesome!! Now what about gaping necklines on knit? You all are such a great resource for all my sewing questions.Thank you!


October 23, 2015 #

Basically the same techniques for any opening, really. :) You can also use clear elastic when you turn and sew a hemmed knit neckline, which will stabilize and bring in the gaping slightly.


October 27, 2015 #

Fab blog, thank you.

I was watching a history documentary this week and was completely distracted by the presenter/historian’s dress pulling/gaping between the bust and sleeve, all I wanted to do was tuck in a little dart to make it sit properly!


October 27, 2015 #

All patterns are made for a “B” cup unless marked otherwise, therefore a Full Bust Adjustment to the pattern will stop the armhole gaping. There are lots of methods to achieve this if you google just that.


November 4, 2015 #

Right – I came here to comment, specifically to add that! There’s a special FBA for t-shirts and other knits, too – do the standard horizontal slice-and-spread at bust level on the pattern (on the Wren, fold out the seam allowances and tape the front band to the bodice pattern, so you alter both the same amount), true the CF lines, and then to add the needed width, draw a shallow semi-circle at the side, also at bust level. Match waist point and/or notches below the bust and at armhole, and gather/ease the extra material in. Marcy Tilton wrote and article on this for Threads magazine in summer in 1996 (“Not your ordinary T-shirt” in I think the July issue . . . I just had it out the other day . . . ).


October 30, 2015 #

I have a question which is not exactly related to this tutorial but to fitting the Wren dress:
I was wondering if it might be a good idea/possible to do a SBA and/or to narrow the shoulder on this pattern? And if so, would you include these issues in a sewalong if you’re planning to do one for the Wren dress?


November 4, 2015 #

Thank you for your knits tips! Just in time for sewing the Wren.