overbust

In corsetry and fitted garment production, overbust is the horizontal circumference taken around a woman's torso at the fullest point of the breasts. Unlike underbust, which sits just below the breast tissue where the ribcage widens, overbust captures the true volume the garment must accommodate. This measurement runs directly across the nipple line and determines how much ease and fabric a corset, bra, or close-fitting bodice requires to sit properly without cutting in or sagging.

The difference between overbust and underbust can range from 2 to 6 inches depending on breast size and shape. A 28-inch underbust woman might measure 34 inches overbust, while someone with a 32-inch underbust could reach 40 inches or more overbust. This gap is critical in corset grading: a corset cut for a specific overbust measurement will not function correctly if made tighter or looser without altering the cup depth and the position of internal stays.

Measurement technique and industry standards

To obtain an accurate overbust, the measuring tape passes horizontally around the body with the subject standing relaxed and breathing normally. The tape sits snugly but not compressed against the skin. Many garment makers take this measurement at the apex of the bust, though slight variations in tape angle can shift the reading by a quarter inch or more. For production, overbust becomes one anchor point; the garment's cup depth, gore width, and side seam shaping all key off this single measurement.

Corset and bra manufacturers typically grade their products in half-inch increments based on overbust. A house might offer sizes 30, 30.5, 31, 31.5 inches and so on, with each size holding the overbust constant while underbust varies in parallel steps. This allows the same cup architecture to serve multiple band sizes without redrafting the entire pattern. Bra cup letters, by contrast, are derived from the difference between overbust and underbust, so a 34 overbust paired with a 30 underbust yields a D cup regardless of absolute breast volume.

Problems arise when sewers or customers confuse overbust with natural waist or treat it as equivalent to ready-to-wear dress sizing. A woman who wears a size 12 dress might measure 36 inches overbust, but corset makers grade independently and do not follow apparel size standards. Custom corsetieres always demand an actual overbust measurement, taken over a thin camisole if needed, rather than a dress size label. Mismatch here leads to finished garments that gap at the sides or cause breast displacement during wear.