Definition
An armhole, or armscye, is the curved opening in a bodice through which the arm passes and into which a sleeve is sewn.
The shape of the armhole decides much of how a garment feels. The front armhole is more deeply scooped than the back, because arms move forward, and a single notch on the front curve and a double notch on the back tell the two apart.
Two measurements matter:
- Armhole depth: from the shoulder point down to the underarm. Too shallow and it cuts in; too deep on a fitted sleeve and you lose movement, because raising the arm then pulls the whole bodice up with it. Fitted woven bodices sit about 2 to 3 cm (3/4 to 1 1/4 in) below the armpit; relaxed and dropped styles sit much lower.
- Armhole length: the seam length around the curve, which the sleeve cap must match, plus its cap ease.
Sleeveless armholes are finished with a facing, bias binding or a lining, and need staystitching right after cutting because the curve is partly on the bias. For sleeved garments, the sleeve and armhole seam allowances are finished together after the sleeve is set in.
The armhole changes with the sleeve style: a drop shoulder moves it down the arm, while raglan and kimono sleeves replace the standard armhole altogether.