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Underwire & Bra-Sized Swimwear Questions

Everything you’re wondering before you get in the water

Sizing, underwire, launch timing, and fit — the questions women ask us most, each with a complete answer that stands on its own. If yours is not here, it will be soon: the list grows from real questions real customers send us.

Three women of different ethnicities in structured underwire swimwear laughing together on sandstone steps beside an arched sea gate
What sizes does Mosona swimwear come in?

We're launching with 30–40 band sizes and DD–H cup sizes. As a small brand, we're starting with the sizes we know are most underserved while ensuring we can deliver the highest quality fit and construction. As Mosona grows, we'd love to expand our size range to J cup based on customer feedback and demand. If you don't see your size yet, join our waitlist and let us know what size you're looking for. It helps us prioritize future expansion.

Why is bra-sized swimwear better than S/M/L swimwear for fuller busts?

Traditional S/M/L sizing is designed to fit a range of body shapes, which makes it flexible—but not necessarily supportive. Two women can both wear a Medium while having completely different bust proportions, making it difficult to achieve a secure, flattering fit. Bra-sized swimwear is designed using both your band and cup size, giving you better support, shape, lift, and comfort. Instead of asking your bust to fit into a general size, the swimsuit is built to fit you.

How do I know my Mosona size if I don't know my bra size?

The easiest place to start is our Bra Size Calculator. Simply enter your measurements and we'll recommend a starting size. Like bras, swimwear can fit differently depending on the style, fabric, stretch, and level of coverage. Your calculator result is a recommendation—not a guarantee. We also recommend checking the fit notes on each product page, where we'll explain whether a style runs true to size, snug, or has more stretch. Still unsure? Reach out to us. We'd be happy to help you find your best fit.

When does the first Mosona collection launch?

The first Mosona collection is in final production now, and waitlist members get first access before the public launch. Joining takes an email address and pays off when early sizes are released — full-bust sizes sell out fastest in swimwear, so the waitlist exists to make sure the women the line was built for get first pick.

Profile of a model with a full bust in an ivory structured underwire bikini top, seamed cups clearly visible, in a warm stone medina lane
Model with a very full bust in a sand structured underwire one-piece standing in a tall arched doorway above the sea
What is bra-sized swimwear?

Swimwear cut and sold by band and cup — a 32G, a 36DD — exactly like a bra, instead of S, M, L. Each band-and-cup combination gets its own engineered cup and firm band, so the suit is built to your measurements rather than an average of many bodies. Every Mosona style is bra-sized; there is no S/M/L anywhere in the line.

Do you make swimsuits for a small band with a large cup?

Yes — that combination is what the brand was built around. The launch grid runs bands 30 through 40 against cups DD through H with no gaps, so a 30G or a 32H is a drafted pattern in the line, not a special order. If stores have been telling you to size up the band to reach your cup, that trade is exactly what Mosona exists to end.

How long does the bra size calculator take?

About 2 minutes: one snug measurement under the bust, one level measurement around the fullest part, and the calculator returns a starting bra size. It is free, needs no email or account, and tells you whether your result is inside the launch range — and if it is not, sharing the size on the waitlist is how the range grows.

Model with a narrow ribcage and very full bust in an olive underwire bikini, leaning against a plaster wall in an arched stone passage
Model reclining on a rooftop terrace ledge beneath a Moorish arch colonnade, whitewashed village and sea behind her at golden hour
Why does Mosona use underwire in every style?

Because the wire is support you can see. It frames each cup so the weight of the bust passes into the band at the ribcage — where about 80% of a bra’s support comes from — instead of hanging off the straps. Past a DD cup, that construction is the difference between a suit that holds through a swim and one that needs constant adjusting.

Where can I buy Mosona swimwear?

Online only, shipping in the United States — there is no physical store. The first collection opens to the waitlist before the public, in the order sizes are cut, so joining with your size is the earliest possible access. Launch and restock news goes to waitlist members first, every time.

Monumental stone archway framing the open sea at dusk, warm plaster walls and stone steps in the foreground

The best answer is trying the suit on

Waitlist members get first access when the collection opens.