Size 34O Bikinis
Also labeled UK 34K and EU 75O
If you wear a 34O bra, start your bikini top search in the same size. Then check that the band stays put and the cups hold you without spilling at the sides. Our Cup-Sized Bikini Size Chart shows how 34O is labeled in UK and EU sizing.
When a 34O Bikini Band Loosens in Water
A band that creeps up your back after a swim on a 34 frame has usually loosened in the water. Check the band after a few minutes in the water, because wet fabric can feel looser than it did dry. You should be able to slide two fingers under the band at the back, but not much more.
Check the top from the side in a mirror. On a mid-range band, the band should sit level from front to back, and the cups should line up with your bust rather than sitting high.
Checking the Cups on 34O Bikini Tops
At this depth, the cups need full coverage at the sides and enough room at the base so the band can sit flat. If the cups feel full but the band rides up, firm up the band before looking at a larger cup. If the cups gap and press at the same time, try a different cup shape before changing size.
On UK labels, this size is 34K. A UK K is a US O, which is four cups larger than a US K.
Testing a 34O Bikini Top as You Move
Raise your arms, lean forward and twist before you decide a top fits. With an O cup, check that nothing slips out at the bottom edge or under the arms. If the top moves, look at the band before you tighten the straps.
Bras in this size: our 34O bras.
Frequently Asked Questions About Size 34O Bikinis
What is a 34O bikini top in UK sizing?
Look for UK 34K or EU 75O, and do not confuse that UK K with a much smaller US K. Read the size system on every tag.
How can I tell if a 34O bikini band is too tight?
It leaves deep red marks, makes a full breath feel hard, or pushes skin over the edge. Loosen it one setting or retie it slightly longer, then check that it still sits level on a mid-range band.
How can I tell if a 34O bikini band is too loose?
It rides up at the back, shifts when you raise your arms, or only feels secure with the straps pulled tight. Tighten or retie it so it stays level on a mid-range band, then check it again after a swim.
What should I check first in a 34O bikini top?
Check the band first. It should sit level and firm on a mid-range band, because the cups and straps can only work once the band is anchored.
Which gives more support in a 34O bikini top, the band or the straps?
The band gives most of the support, and the straps only steady the cups. With an O cup, a firm band is what keeps the straps from digging in.
Should the straps hold up a 34O bikini top?
No. The band should do most of the work, and the straps only steady the cups. If you need tight straps in 34O, the band is likely too loose.