Definition
A sleeve cap is the curved upper part of a set-in sleeve, between the front and back underarm points, that is sewn into the armhole and shapes the shoulder.
The sleeve cap is shaped like a bell: highest in the middle, where it meets the shoulder seam (marked by a dot or notch), and curving down to the underarm on each side. Its height decides the balance between a neat look and freedom of movement.
| Cap height | Look and feel |
|---|---|
| High, about 14–16 cm (5 1/2–6 1/4 in) | Smooth, fitted sleeve that hangs close to the arm; less reach |
| Medium, about 12–14 cm (4 3/4–5 1/2 in) | Everyday blouses and dresses |
| Low, about 10–12 cm (4–4 3/4 in) | Flatter cap, more movement; T-shirts, sweatshirts, shirts |
The exact figures depend on the size and the armhole, but the principle holds: the higher the cap, the more fitted the sleeve; the lower, the more freedom when you raise your arms.
On a woven set-in sleeve, the cap's seam line is a little longer than the armhole. That surplus, the cap ease, is eased in so the sleeve rounds over the shoulder without puckers. Puff sleeves add much more length and gather it instead.
Match notches carefully: single notch to the front, double notch to the back, top dot to the shoulder seam. Full instructions are in setting in sleeves without puckers; the alternatives are the raglan sleeve and the drop shoulder.