The Short Answer
A strapless bra is a fully engineered bra — underwire, molded cups, silicone grip strips, rigid underband — that happens to have no straps. A bandeau is a simple tube of fabric with no cups, no wire, and no structure. Both lack straps, but a strapless bra provides real support while a bandeau provides virtually none.
Construction Side by Side
| Feature | Strapless Bra | Bandeau |
|---|---|---|
| Cups | Molded, defined | None — flat fabric |
| Underwire | Almost always | Never |
| Grip mechanism | Silicone strips, rigid band | Elastic only |
| Structure | High — engineered to stay up | Minimal — relies on stretch |
| Support | Moderate to good | Almost none |
| Cup sizes | A through G+ | One-size or S/M/L |
| Price | $30–70 | $8–25 |
How to Tell Them Apart
Hold them up. A strapless bra has visible cup shaping — it holds the cup form even off the body, like a regular bra without straps. A bandeau lies flat — it's literally a rectangular tube of fabric with no dimensional cup shape.
When to Wear Each
Strapless bra: Under strapless dresses, off-shoulder tops, tube tops where you need actual support and a defined bust shape. The only real choice for C+ cups under strapless garments.
Bandeau: As a light coverage layer under sheer tops, over a swimsuit, or as a casual lounge piece. Best for A–B cups who want coverage without structure. Also popular as a layering piece over another bra for visible-lingerie styling.
History
The bandeau is one of the oldest bra forms — ancient Roman women wore a "strophium," a fabric band wrapped around the chest, which is essentially a bandeau. The modern strapless bra is a 1950s engineering achievement, born from the need to wear bras under the strapless evening gowns that became fashionable in the late 1940s.