Side to side across the base, where tissue meets the chest wall.
From the chest wall straight out to the furthest point.
Enter both measurements to continue.
Width versus depth
Projection compares how far tissue extends outward to how wide it spans at the base. Two breasts with identical volume can have very different ratios — one wide and shallow, another narrow and deep — and that ratio is what drives whether a cup gaps or fits snugly.
< 0.8 = shallow · 0.8–1.1 = average · > 1.1 = full
This is a rough categorization for style guidance only — it isn't a precise clinical measurement, and plenty of people fall right at the edge of two categories.
Matching cup styles
What each category tends to suit
Wide and flatter tissue
Demi, balconette, or t-shirt styles with a shallower cup tend to fit smoothly, avoiding excess fabric at the top that deeper cups can leave.
Balanced width and depth
Most standard cup shapes — balconette, full cup, plunge — generally work well without major adjustment.
Deeper than wide
Cups with more depth built in hold this shape better; shallow, moulded cups are more likely to gap at the top.
Right between two categories
Try both neighbouring style recommendations and let actual fit — not the category label — make the final call.
Questions
Projection FAQs
How far tissue extends outward from the chest wall, compared to how wide it spans side to side — independent of overall cup size.
Root width is measured side to side across the base of the bust; projection depth is measured from the chest wall straight out to the furthest point.
Yes — two people with the same cup letter can have quite different projection, since cup size measures volume difference, not shape.
A cup built for full projection has extra depth that a shallower, wider shape doesn't fill, causing gapping at the top even at the right volume.
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