Size 40N Bikinis
Also labeled UK 40JJ and EU 90N
Holding a very deep cup on a large band takes a bikini top sized like a bra, which is what 40N gives you. Check the fit dry and again after a swim, since wet fabric can relax. Compare brands and labels in our Cup-Sized Bikini Size Chart.
Checking the Band on 40N Bikini Tops
A 40 band spans a wide back, and a bikini band that is even slightly loose will move as soon as you swim. If the band presses into your sides, check that it is not set too tight to make up for loose cups. When the band is right, the cups stay in place and the straps can stay relaxed.
With a very deep cup, lean forward and check that each cup still holds you. If tissue slips under the band, the band usually needs to be firmer.
Side Coverage for a 40N Bikini Top
Wide straps can feel kinder on the shoulders with an N cup, as long as the band is doing its share. If the cup edge digs in across the top, settle your bust again before deciding the cup is too small. Loose fabric at the top of the cup can mean it is a little deep for you, or the shape is wrong.
Its UK label is 40JJ. The doubled JJ sits between a UK J and a UK K.
Choosing Bikini Bottoms Separately From 40N
A 40N top tells you nothing about the bottom size you need. Many people wear a different size top and bottom, and that is normal. Pick bottoms by the coverage and rise you like, using their own measurements.
Looking for everyday support as well? Try our 40N bras.
Frequently Asked Questions About Size 40N Bikinis
How does 40N convert to UK and EU bikini sizes?
In UK sizing 40N reads 40JJ, since UK charts never use N, and EU sizing keeps 90N. Check which system each brand uses.
Does a 40N bikini top need wide side coverage?
Yes, usually. With a very deep cup, tissue can slip out near the underarm when you move, so look for cups that reach back toward your side.
How can I ease neck strain from a 40N halter top?
Firm up the band first so it carries more of the weight, then loosen the halter a little. If your neck still feels the pull with a very deep cup, shoulder straps spread the load more comfortably.
Should I buy bikini bottoms in 40N?
No, bottoms are not sized by band and cup. Use the bottom's own size guide and pick it by your hips and the rise and coverage you like.
Why do 40N bikini cups gap at the neckline?
A gap at the top often comes from cup shape rather than size. With a very deep cup, compare a lower or fuller coverage cut before you go down a cup.
Why does the top edge of a 40N cup dig in?
The cup most likely needs more depth. Settle your bust again first, and if the edge still cuts in on a large band, compare a deeper or fuller cup.