ISMÊ Swim Sizing Guide: How to Get It Right First Time

There is a specific reason this guide exists, and it is not that ISMÊ sizing is unusually complicated. It is that ISMÊ does not do exchanges.

Not "exchanges are slow" or "exchanges cost extra". Their policy says plainly that they do not process exchanges at all, because inventory is limited. If your size is wrong you return it, pay the return shipping yourself, wait for the refund, and then buy again at whatever is still in stock. On limited drops, that often means the print you wanted is gone.

So ordering the right size the first time is worth more here than at most swim brands. Here is everything you need to do that.

The short version

• Tops run slightly small. Stay true to size unless you are tall

• Bottoms are Brazilian cut, meaning cheekier and higher-cut than most US brands. Size up if you want more coverage

• If you are 5'6" or taller, size up on both. If you are 5'3" or under, you may want to size down for a more minimal fit

• Between sizes on bottoms? Size up. Between sizes on tops? Stay true

• Sale and promotional items are final sale, so there is no safety net on discounted pieces

The size chart for tops

ISMÊ sizes tops by cup size and jeans size rather than by measurement. Here is how their chart maps out:

Size

Cup size

US jeans

Notes from the brand

XS

AA to A

00 to 2

Best for petite frames

S

A to B

2 to 6

True to size for most

M

C

7 to 8

Ideal for C cups

L

D

8 to 10

True to size

XL

DD and up

11 to 12

Recommended for DD cups

One honest limitation worth knowing: ISMÊ does not publish actual bust or underbust measurements in inches or centimetres anywhere on their product pages. That is unusual for a swim brand and it makes the usual trick of measuring yourself and matching the chart impossible. You are working from cup size and jeans size alone.

If you sit awkwardly between the two, for example a small band with a larger cup, that gap matters. See the section below on contacting them directly, because that is genuinely the best route in that situation.

The size chart for bottoms

Bottoms are sized purely by jeans size:

Size

US jeans

Coverage

Notes

XS

00 to 2

Brazilian

Mid-rise

S

2 to 6

Brazilian

Mid-rise

M

7 to 8

Brazilian

Mid-rise

L

8 to 10

Brazilian

Mid-rise

XL

11 to 12

Brazilian

Mid-rise

The brand describes the cut as moderate to cheeky Brazilian coverage with a mid-rise fit, and says it is true to size for most of their customer base. Their explicit advice for anyone in between: size up, especially if you are 5'6" or taller.

What Brazilian cut actually means for coverage

This is the part that surprises people, and ISMÊ is upfront about it in their own words: their bottoms offer cheekier, higher-cut coverage than most US brands.

If you normally wear US swim brands, expect noticeably less rear coverage than you are used to at the same nominal size. That is the design intent, not a manufacturing issue. The brand is California-based but designed by a Brazilian, and the cut follows Brazilian beach convention rather than American.

Two practical consequences. First, if you want US-style coverage, size up one from your jeans size and accept a slightly looser fit at the waist. Second, if you are buying for a context where you want more coverage, such as a family holiday or a beach with a conservative dress code, factor that in before ordering rather than after.

The height rule, which matters more than people expect

ISMÊ gives height-based guidance that most brands skip, and it is worth following:

• 5'6" and taller: size up. Longer torso and longer leg line means the same piece sits higher and covers less on you than on a shorter frame

• 5'3" and under: you may want to size down for a more minimal fit, if minimal is what you want

• In between heights: follow the cup and jeans size chart as written

The tall guidance applies to both tops and bottoms. On a triangle top it is about the halter strap length and where the triangles sit; on bottoms it is about rise and rear coverage.

Triangle top versus underwire top

The triangle top is a classic triangle fit with adjustable halter and back ties, so there is meaningful room to fine-tune the fit after it arrives. That adjustability is why the brand says it runs true for most people despite the slightly small cut.

The underwire top costs a little more, $46.50 against $43 for the triangle, and offers more structure. If you are a D cup or above and want actual support rather than just coverage, that is the one to look at.

One returns detail that catches people out: if you try on a tie top and adjust the ties, you need to untie them again before sending it back. Their policy specifically requires items to be returned untied and in the original ziplock.

Ask them directly, because it works

ISMÊ invites customers to contact them for personalised sizing help, and given that they do not publish measurements, this is genuinely the most reliable route if you are uncertain.

Send them three things: your bra size, your jeans size and your height. That is exactly what they ask for. They handle these questions through Instagram.

For a $43 piece that cannot be exchanged, a message before ordering is a sensible use of five minutes.

The returns policy, in full, because it shapes everything

This deserves its own section since it is the reason getting sizing right matters so much here.

• You have 15 days from delivery to return. Not 30

• There are no exchanges at all. Return and rebuy separately

• You pay return shipping. They do not provide prepaid labels

• The hygiene liner must still be attached, and tags must be on

• Items must be unworn, unwashed and free of any stains. Their policy states this in capital letters with no exceptions

• No odours or product residue, which specifically includes lotion, perfume and self-tanner

• Items must be returned untied and in the original ziplock

• Anything bought on sale, during a promotion, or at a discounted price is final sale and cannot be returned

• Refunds go to the original payment method. No store credit option

• Refunds process 2 to 5 business days after arriving at their returns centre in San Diego

The self-tanner clause is worth highlighting because it catches a lot of people. If you try swimwear on after applying tan, even lightly, you have likely lost the ability to return it.

A practical ordering strategy

Putting all of it together, here is the approach that gives you the best chance of one order and no returns:

• Work out your jeans size and bra size honestly, not aspirationally

• Check your height against the rule above and adjust up if you are 5'6" or over

• Decide how much rear coverage you actually want, remembering these run cheekier than US brands, and size up on bottoms if you want more

• Choose the triangle top if you want adjustability, the underwire if you want support

• If anything about your measurements is borderline, message them first with height, bra size and jeans size

• Buy full price rather than on sale if there is any doubt about fit, because sale items cannot be returned at all

FAQs

Does ISMÊ Swim run small?

Tops run slightly small by the brand's own description, though the adjustable ties compensate for much of it. Bottoms run true to size for most people but with much less coverage than US brands due to the Brazilian cut.

Should I size up in ISMÊ Swim?

Size up on bottoms if you want more coverage or if you are 5'6" or taller. Stay true to size on tops unless you are tall. If you are between sizes anywhere, their own advice is to size up.

What size range does ISMÊ Swim carry?

XS through XL, mapping roughly to US jeans 00 through 12 and cup sizes AA through DD and above.

Can I exchange ISMÊ Swim for a different size?

No. The brand does not process exchanges, citing limited inventory. You return the item for a refund and place a new order separately, which means the size you want may sell out in the meantime.

How long do I have to return ISMÊ Swim?

15 days from delivery, with the hygiene liner and tags attached, no stains or product residue, returned untied in the original ziplock. You pay return shipping.

How much does ISMÊ Swim cost?

Individual pieces run roughly $43 to $46.50. Triangle tops and Brazilian bottoms are $43 each, adjustable bottoms $44, underwire tops $46.50, so a full set lands around $86 to $90.

Is ISMÊ Swim good for bigger busts?

The range goes to XL, listed for DD and above. The underwire top is the better choice over the triangle if you need structure. Since they do not publish underbust measurements, messaging them with your bra size before ordering is worthwhile.

Final word

ISMÊ makes genuinely distinctive swimwear at a fair price, and the sizing itself is not difficult once you know the two rules: tops slightly small, bottoms cheekier than you expect.

What makes it worth taking seriously is the returns structure. A 15-day window, no exchanges, buyer-paid return shipping and final sale on anything discounted means a wrong size is a real cost rather than a minor inconvenience. Spend the time on the chart, use the height rule, and message them if you are unsure. One careful order beats one return you cannot exchange.