F Cup Bras

The cup letter describes the gap between your bust and band, so it only means something alongside a band number:

• UK sizing runs A, B, C, D, DD, E, F. That is three steps past D, so a UK F is a genuine full-bust size.
• US sizing reaches the same volume in fewer steps and calls it a G — the US run is D, DD, DDD, G. So a UK 34F is a US 34G.
• EU sizing also labels this volume G, on a centimetre band: a UK 34F is an EU 75G.
• Most F cup bras sold in the US are UK-sized, because the houses that make this size — Freya, Fantasie, Panache, Cleo — are British. Assume UK unless a brand says otherwise.
• The band drives volume: a 28F and a 44F share a letter and hold very different amounts, because every cup is cut in proportion to its band.

Two measurements set your size, and one trick fixes most fit problems:

• Underbust — measure snugly around the ribcage directly beneath the bust, tape level all the way round. This gives your band.
• Bust — measure around the fullest point without compressing. The difference between the two gives the cup.
• Sister sizing — if the cup fits but the band does not, move across: down a band means up a cup, and vice versa. A 34F, a 32FF and a 36E all hold the same volume.

If you land between two bands, take the smaller one and go up a cup. A slightly firm band stretches into place; a slightly loose one only gets looser, and at F cup that means the straps end up carrying weight they were never designed for. For the full walkthrough, see our guide to measuring your bra size, or convert a size you already own with the bra size converter.

Support at a full bust comes from engineering, not luck. The features that separate a bra that works from one that does not:

• A firm, mostly non-stretch band — it does most of the support work. Snug and level on the loosest hook, so you can tighten it as it stretches.
• Wire that fully encircles the breast — sitting flat on the ribcage behind the breast, never on tissue. Wire on tissue means the cup is too small, not that wires do not suit you.
• Three-part or side-support cups — seamed cups project and contain better than moulded ones as you go up, though at F a well-made moulded cup still works.
• Fully adjustable straps — to spread load. Deep grooves mean the band is failing, not that the straps are too thin.
• Three or more hooks — a deeper back distributes tension instead of concentrating it.

This is the one category where getting it wrong has physical consequences. Breast tissue has no muscle to support it, and at F cup unsupported movement during running strains the ligaments over time.

• Encapsulation is not optional — separate moulded cups that hold each breast individually. Compression-only styles that work at smaller cups flatten rather than support and do not control movement at F.
• Best in class combines both — encapsulation for control plus light compression for stability.
• The band should be wider and firmer than your everyday bra, with no stretch through the underband.
• Replace them more often than you think — a sports bra loses meaningful support long before it looks worn.

Browse the full sports bra range and filter to your band.

F is well served by the full-bust specialists, and they differ in useful ways. Freya and Fantasie lead on pretty, design-led styles with reliable construction; Panache is the everyday backbone with firm bands and three-part cups; Cleo is the younger, more design-led line from the same house; Sculptresse extends into the wider bands. Between them the F range spans t-shirt, plunge, balconette, strapless and sports.

To make an F cup bra last: hand-wash in cool water or use a mesh bag on a delicate cycle, fasten the hooks first so they do not snag, never wring a moulded cup, and lay flat or hang to dry. Heat destroys elastic faster than wear does, so keep them out of the dryer. Rotating three bras rather than wearing one on repeat roughly doubles the life of each.