Size 38O Bikinis
Also labeled UK 38K and EU 85O
With an O cup, a bikini top needs real depth and side coverage, and 38O is sized for exactly that. Look at how the back fastens, too, since ties and hooks feel different. See our Cup-Sized Bikini Size Chart for the labels other brands use.
How a 38O Bikini Band Should Feel
Ties can be adjusted to any length, but on a 38 band they can work loose under the weight of the cups. Most bands that ride up after a swim were a little loose to begin with. Set the band before you touch the straps, since the straps can only fine tune the fit.
Give the 38O top a test at home: wear it while you sit, reach and bend. If the band stays put and the straps stay comfortable, the fit is right.
When 38O Bikini Cups Gap or Spill
Do not judge an O cup by the front view alone; turn sideways and check the cup reaches all the way back. Settle each side into the cup, then raise your arms and check that nothing slips out at the side or bottom. The middle of the top should rest near your chest, not float away from it.
UK brands print it as 38K. A UK K is a US O, which is four cups larger than a US K.
Halter or Shoulder Straps for 38O
If a halter top pulls hard on your neck, the ties are carrying weight the band should hold. Firm up the band first, then loosen the halter a little. For 38O, straps that sit over the shoulders often spread the load more comfortably.
Shopping for everyday wear too? Browse our 38O bras.
Frequently Asked Questions About Size 38O Bikinis
What is a 38O bikini top in UK sizing?
US 38O is labeled UK 38K and EU 85O, and that UK K is four cups larger than a US K. Read the size system on every tag.
Which gives more support in a 38O 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 38O bikini top?
No. The band should do most of the work, and the straps only steady the cups. If you need tight straps in 38O, the band is likely too loose.
How should a 38O bikini top feel after swimming?
It should feel close to how it felt dry, with the band level and the cups still covering you. If the band feels loose after a swim, it was probably a little loose to begin with, and on a larger band that shows quickly.
Is it normal for 38O to fit differently between bikini brands?
Yes. Brands cut bands and cups differently, so a 38O top can feel firmer in one style and roomier in another. Use each brand's chart and judge the fit on you.
How can I check a 38O bikini top fit at home?
Put the top on, lean forward to settle into the cups, then stand and check the band in a side mirror. Raise your arms and twist, then look for movement at the band or spilling at the edges.