Swimwear Size Chart
| US | UK | EU |
|---|---|---|
| 4 | 8 | 36 |
| 6 | 10 | 38 |
| 8 | 12 | 40 |
| 10 | 14 | 42 |
| 12 | 16 | 44 |
Sizing conventions vary by brand and cut. See how this chart is compiled.
Swimwear sizing runs its own numbers, separate from everyday clothing size
A swimsuit is frequently cut and labelled on a different size scale than the same brand's regular clothing line, since stretch fabric, chlorine exposure, and the garment's specific construction all behave differently from woven or knit daywear — assuming your everyday dress or trouser size converts directly into that brand's swimwear size is a common and avoidable mistake.
Stretch percentage changes how literally to read the size chart
Swimwear fabric blends vary in how much stretch they're built with — a high-stretch four-way fabric tolerates a size range more forgivingly than a lower-stretch fabric closer to standard woven material — so a size chart's numbers on a highly stretchy suit function more like a midpoint of a comfortable range than an exact fit boundary, while a less stretchy suit needs closer adherence to the printed number.
One-piece and two-piece swimwear can need different sizes on the same body
A two-piece swimsuit lets the top and bottom be sized completely independently to match different parts of the body, while a one-piece has to compromise across bust, waist, and hip in a single garment — someone whose bust and hip proportions differ noticeably from that brand's assumed one-piece ratio may find a two-piece a more reliable fit path than forcing a single size to work across the whole body.
Board shorts and men's swim trunks size closer to general clothing waist size
Unlike most swimwear, men's board shorts and swim trunks are frequently sized against the same waist-inch convention used for general trousers rather than a swimwear-specific scale, since the garment's loose, non-compression fit doesn't need the same specialized sizing logic that a fitted swimsuit does — the standard waist-size conversion elsewhere on this site applies more directly here than to fitted swimwear.
Competitive and technical swimwear is deliberately sized far tighter than leisure swimwear
A competitive racing swimsuit is engineered to fit extremely snugly by design, for compression and reduced drag, meaning its size chart numbers run noticeably tighter than a leisure swimsuit's chart at the same stated size — converting a leisure swimwear size directly into a competitive brand's chart typically produces a suit that's too loose for its intended performance purpose.
Kids' swimwear follows the same age/height ambiguity as general children's clothing
Children's swimwear carries the same age-versus-height sizing unreliability covered on the kids'-clothing chart, compounded by the fact that swimwear is worn without the layering that can hide a slightly-off fit elsewhere — checking a specific brand's height/weight figures rather than the age label alone matters as much here as for any other kids' garment.
Maternity swimwear follows current measurements, not a pre-pregnancy reference size
Maternity swimwear is sized against a pregnant body's current measurements at the time of purchase, generally with room built in for continued growth through the remaining pregnancy, rather than any pre-pregnancy reference size — buying based on current measurements close to when the suit will actually be worn, rather than early in pregnancy, produces a more reliable fit.
Rash guards and sun-protective swimwear size closer to activewear than fitted swimwear
A rash guard or full-coverage sun-protective swim top is typically cut with the looser, more athletic-fit assumptions of general activewear rather than the closer, compression-oriented fit of a fitted swimsuit, since its main job is UV coverage and mild abrasion protection rather than a sculpted silhouette — sizing it more like a fitted rash-guard top or light activewear top tends to be more accurate than sizing it like a swimsuit.
Wetsuit-adjacent swim gear (triathlon suits, swim skins) needs a snugger reference than casual swimwear
A triathlon suit or swim-skin garment, built to reduce drag in open water, is meant to fit considerably tighter against the body than casual leisure swimwear at a nominally matching size, closer to the snug-fit logic covered on the wetsuit chart elsewhere on this site than to a beach swimsuit's more relaxed fit assumption.
Swimwear labelled by cup size follows the bra-sizing logic, not a separate scale
A swimsuit top offering cup-lettered sizing (rather than a simple S/M/L) generally follows the same band-and-cup logic covered on the bra chart elsewhere on this site, including the same sister-sizing flexibility between adjacent band-and-cup combinations — that chart's conversion logic, not a swimwear-specific cup scale, is the more useful reference for this style.
Chlorine and saltwater exposure change fit over a swimsuit's lifespan, not just at purchase
Repeated chlorine or saltwater exposure gradually breaks down the elastane in swimwear fabric, so a suit that fit snugly when new can loosen measurably over a season of regular pool or ocean use — this is a fabric-aging effect rather than a sizing error, and buying true-to-size initially (rather than compensating in advance for expected future loosening) still produces the better overall fit across the garment's life.
Swim briefs and men's fitted swimwear size closer to underwear conventions than trunks do
A fitted swim brief or jammer-style suit sizes closer to the compression logic of fitted underwear than to the looser board-short convention, so a man moving between a loose trunk style and a fitted brief style within the same brand should expect the two size charts to diverge meaningfully rather than assume one converted number serves both styles.
Adaptive and post-surgical swimwear follows a specialized category of its own
Swimwear built with adaptive features — easier closures, coverage for medical devices or post-surgical needs — is generally cut and sized around those specific functional requirements rather than the standard bust/waist/hip logic this chart otherwise covers, so a specialist adaptive-swimwear retailer's own guidance is the better resource rather than converting a standard swimwear size into this category.
Frequently asked questions
Does my regular dress or trouser size convert into the same brand's swimwear size?
Not directly, and when the two disagree it's rarely at random — a brand's swimwear line commonly runs a size or two smaller in the number than its own daywear, on the assumption that the stretch fabric compresses to the body rather than sitting at ease the way a woven dress does, so starting from your daywear number and expecting to size up is a safer default than assuming a 1:1 match.
Should I read a stretchy swimsuit's size chart as literally as a less-stretchy one?
Not literally, and there's a rough way to tell before ordering which kind of number you're working with: a fabric description emphasizing four-way stretch or a high listed elastane share is the forgiving end of that spectrum, while a suit described as shape-retention or built mostly from nylon with only a small stretch share behaves much closer to a fixed boundary.
Do men's board shorts use swimwear-specific sizing or regular trouser sizing?
Regular waist-inch sizing generally, though a board short's drawstring or hybrid elastic-and-tie waistband is built to take up meaningfully more slack than a trouser's own waistband — so a borderline call on the printed chart is more forgiving here than the identical borderline call would be on a pair of jeans, precisely because the closure itself is designed for adjustment.
Can I use my leisure swimwear size to buy a competitive racing suit?
No, and there's a simple check once you have one on: pinching the fabric away from the hip or ribcage should give very little slack — a suit that lifts away easily is too loose for genuine racing compression regardless of what its printed size said, which is why many competitive swimmers try a suit on before a meet rather than trusting a converted number alone.
Is kids' swimwear sizing more or less reliable than general kids' clothing?
Kids' swim lines commonly step in narrower brackets than the same brand's everyday clothing — a one-year age step rather than the two-year step common in general kids' wear — so a child sitting right at the edge of a general-clothing age band is more likely to land cleanly inside one specific swim bracket instead of straddling two.
Should maternity swimwear be sized to my pre-pregnancy size?
No. Some maternity suits also build in a drawstring or adjustable side-tie at the hip seam specifically so one suit can be worn from around the fifth month through to full term, which is worth checking for on the product page before assuming a second suit will be needed later in the pregnancy.
Should I size a rash guard like a swimsuit or like activewear?
More like activewear. Because rash guards borrow activewear's alpha (S/M/L) sizing rather than a numeric swimwear scale, they typically run generous through the shoulder and short through the torso by design, so someone who normally sizes down for a snug fitted swimsuit often needs their usual size, or even one size up, to keep full torso coverage once the arms are raised for paddling.
Should a triathlon suit fit as loosely as casual swimwear?
No. Most triathlon federations also regulate suit panel thickness by race distance — thinner, more flexible neoprene panels are typically permitted for shorter sprint-distance events and thicker buoyancy panels for longer ones — so the same body measurements can call for a different suit model built for your race distance, not just a different size within one model.
Does a cup-lettered swimsuit top follow its own sizing scale?
No. A cup-lettered top and a padded-but-unlettered top solve the same support problem through two different mechanisms — the padded version relies on foam or removable inserts rather than a graduated cup shape — so comparing the two is really comparing two different products, not two labels for one sizing system.
Do swim briefs use the same size chart as board shorts from the same brand?
No. Beyond the compression difference, a brief or jammer also sits at a distinctly lower rise than a board short, so the leg opening and where the waistband actually lands on the body will feel unfamiliar the first time you switch styles, even once the size itself converts correctly.
Can I convert a standard swimwear size into adaptive or post-surgical swimwear?
Not reliably, and the reference point itself often differs — several adaptive swimwear lines size against standard dress-size numbers (the same convention used for general clothing) rather than the bust/waist/hip swimwear logic covered throughout this chart, so converting from a regular swimwear size can point you at the wrong reference system entirely, not just the wrong number within the right one.
Do swim caps follow their own separate sizing logic from swimwear generally?
Yes — a swim cap sizes primarily against head circumference and hair volume rather than the bust/waist/hip figures this chart covers, and silicone caps in particular offer far less give than a fabric or latex cap, so someone with thick or long hair is generally better served by a size labeled for that specifically rather than a generic one-size cap.
Does a swimsuit's colour (especially darker or patterned fabric) affect its actual fit or stretch?
No — colour and print are a dye and finishing choice with no bearing on the underlying fabric's stretch or recovery, so two suits in the same style, size, and material but different colourways fit identically regardless of shade or pattern.