Ease

Wearing ease is the amount needed to move, breathe and sit down — without it a garment measured exactly to the body is unwearable. Design ease is everything on top of that, and it is a style decision rather than a fitting one: the same block makes a fitted shirt and an oversized one by changing nothing but the design ease.

There is a third kind that catches people out. Sleeve cap ease is the small surplus in a sleeve cap over the armhole it sets into — usually one to two centimetres on a shirt — which is eased in rather than gathered, and it is what gives a set-in sleeve its shape over the shoulder.

Ease is also why no software can promise fit. Fit depends on ease, on fabric behaviour and on whose body it is; geometry is the part that can be guaranteed.