What’s in a Gusset?

A funny name for a little triangle of fabric, the thumb gusset is the difference between mittens that fit and uncomfortable hands.

Pat Olski Dec 5, 2023 - 5 min read

What’s in a Gusset? Primary Image

A simple thumb gusset makes the Columbia Mittens fit comfortably. Photo by Gale Zucker

The anatomy of a functional mitten is so interesting for something that is, at its essence, pretty simple to knit. A well-designed cuff provides air and weather tightness, and a secure fit; an ample width around the hand allows air to circulate for warmth; well-planned tip shaping allows for comfort and for the hand to flex; and the fourchette and the thumb gusset allow the thumb and the fingers to have a full range of motion. (More on the fourchette later.)

Pink mitten in process with stitches held on waste yarn A thumb gusset is a triangle of knitted fabric oriented so that the apex of the triangle faces the wrist. Photos by Katrina King

What is a thumb gusset, anyway?

A thumb gusset (in hand coverings that are knit in the round) is a triangular piece of fabric that is oriented so that the apex of the triangle faces the wrist, and the base of the triangle is directly under the thumb. This additional fabric allows for movement, so that the thumb isn’t bound next to the hand, and so that the yarn won’t break at that particular point of stress.

It is constructed by means of paired increases which are usually placed on each side of a single stitch. The gusset placement can occur at any part of the round at the spot where the thumb will eventually be knitted on depending upon the pattern, although the thumb and gusset placement is most commonly knitted at (or near) the beginning or the end of a round.

It is helpful to place stitch markers, one to the right and one to the left of this foundation stitch; you can then continue to move them so that there is one at each edge of the gusset as becomes wider.

Because the thumb gussets in some patterns may be fully fashioned (meaning that the increases are design elements that will show), it is important to select the right leaning and left leaning increases that you like the best and that best complement your style of knitting.

If you prefer less obtrusive increases, M1R and M1L (which are made by knitting an increase in the running threads either before or after the stitch that is to be worked), will create increases that are less visible on the surface of your knitting. (For descriptions of M1R and M1L increases, see

A thumb gusset can also be an imaginative place to add a decorative element, and that little triangular piece is sometimes decorated with motifs in colorwork, or a lacy leaf, cable, or surface patterning in solid color knitting.

Pink mitten in process on double-pointed knitting needles When you have finished knitting the thumb gusset and any plain rounds called for in the pattern, you'll put the thumb stitches on hold and knit the rest of the hand.

Once you have worked the specified number of rounds, and the thumb gusset has reached the desired size, the pattern may call for you to knit a few rounds without any additional increases. You will place the live stitches on a length of scrap yarn (smooth cotton yarn in a contrasting color is ideal for this purpose), or you can place them on a stitch holder. I often use locking markers to hold my thumb gusset stitches until I am ready to knit them as part of the thumb on a subsequent round.

What about the rest of the mitten?

In general, the rest of the mitten or glove is usually finished in its entirety before the thumb gusset stitches are slid from the holder onto dpns along with the specified number of cast on stitches that make up the fourchette (a small, sometimes triangular piece that adds ease at the base of the thumb and fingers). The thumb gusset and fourchette stitches will form the beginning round of the knitted thumb. Using a smaller size set of dpns for the first round or two of the thumb can help counteract the difference in tension that comes from moving the stitches from a holder onto dpns.

Experiment with different increases, and you will be amazed at the amount of fine detail that you can add to your hand made mittens and gloves.

Discover the wonder of the thumb gusset in the Columbia Mittens.

Pat Olski is a knitter, needleworker, and the editor of PieceWork magazine.