40D Bra Size, Fully Explained
40D is a fuller-band size in the strong middle of the cup ladder, well served by comfort and support ranges. Construction quality matters more than fashion here: taller side wings and three-hook bands separate all-day sizes from afternoon regrets.
40D in every sizing system
| US | UK | EU | FR | AU | JP | KR |
|---|---|---|---|---|---|---|
| 40D | 40D | 90D | 105D | 18D | E90 | E90 |
Sister sizes of 40D
Each sister holds roughly the volume of 40D on a different band. Band riding up in a 40D? Try 38DD. Band digging painfully? The other direction.
How 40D compares, visually
Circle areas scale with estimated cup volume: 40D ≈ 869 cc per cup, roughly 0.8 kg of tissue per side at typical density. Model documented on the weight page.
Is 40D big?
Is 40D big? It is close to the middle of the real-world distribution: commonly reported averages in the US and UK land within a letter of this size, though survey methods vary widely. On a 40 band this difference is proportionate rather than dramatic, whatever cup-letter folklore suggests.
Shopping notes for 40D
Confirm the size first: two minutes with the calculator beats inheriting a label. Then let the brand decoder translate 40D into each brand's cut, since the same tag runs shallow at mall brands and deep at UK houses. If 40D passes the band checks but the cup misbehaves, that is usually shape, not size.
Frequently asked questions
Last updated August 2026.