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Why is an Underarm Gusset Good?

Here’s your 40 second visual rundown on just what an underarm gusset does in a simple smock/shift/chemise/shirt pattern. I have two very simple smocks here – one eleventh century style, a la Kohler, and the other more of a sixteenth century style, adapted from Arnold. There’s a drastic difference in the fit at the shoulder.

closeup of two smocks
The smock without the underarm gusset (left) has more fabric bulk at the shoulder.

The Kohler smock is not quite a T-tunic cut – it actually sets the sleeve at a slight angle to add some extra fabric for movement under the arm. The second smock uses a relatively large underarm gusset. (It’s a faked gusset, mind you, because the 1″ square gusset I was trying to set defeated me. It achieves the correct shape.)

smocks shown with arms extended
When you straighten out their little dolly arms, you can see what the gusset does.

By adding the gusset, we add a lot more ease under the arm. That prevents the smock from bunching around the arm when the arm is lowered, as well as giving us a much wider range of motion. (The dolly on the right could play basketball in her little smock, while the other would have to be careful how she tried to move her arms.)


  1. JNormann
    JNormann May 19, 2014

    I love gussets. You can add a gusset to an existing garment (fabric matching might be difficult, but doable..sometimes) to give a little more ease to the arm. I hate dresses and blouses that raise up entirely when I raise my arms. When you draft your pattern you can add the gusset to the pattern; when adding in later it is more of a diamond shape whose width is dependent upon the amount of ease you require.

    • missa
      missa May 19, 2014

      Good point on the shape of gussets added after the fact, JL. The diamond shape is traditional even for gussets added during sewing. It’s easy to find a square of fabric, and then the bias of the fabric is running in the direction of reaching up or out – right where the stretch is required!

  2. Sassy Lass
    Sassy Lass April 29, 2015

    your post makes me think of suit jackets – and how limiting they are when you need to raise your arms higher than chest height . So why don’t they add gussets to suit jackets to improve range of motion? I mean is there a downside to adding gussets since it seems like all positive reasons to add a gusset?

    • missa
      missa May 2, 2015

      Hi, Marisa – I couldn’t say for sure. I think they don’t do it because traditionally, if you’re in a well-fitted suit coat, you’re supposed to be important enough that you don’t really have to do manual labor.

  3. Ista
    Ista June 2, 2015

    I think it’s more that a well fitted jacket has the undearm cut high enough so that you can raise your arm properly.

    • missa
      missa June 6, 2015

      Hi, Ista – Fit and the cut of the underarm curve are good points, although I still think you should expect some limitation of movement while wearing a suit. ;) I do find that a lot of off-the-rack jackets have a fairly stingy cut across the deltoid, which can impact movement as much as a poorly done underarm curve. (I know there are girls in my size range with relatively dainty upper arms, but it doesn’t feel like a fair assumption. It’s right up there with jeans my size cut with no allowance for an actual ass.)

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