How to Measure for Swimwear (The Only Measurements That Matter)
Tools & Setup
Use a soft fabric measuring tape and measure on bare skin or over thin underwear. Stand naturally, keep the tape level (parallel to the floor), and measure snug but not tight. Swim fabrics stretch when wet, but a good suit should still feel secure when dry.
Tip: If you are between sizes, choose based on your largest measurement (often hips or bust). For one-pieces, prioritize torso length.
Measure around the fullest part of the bust. Keep tape level and comfortable.
Measure around ribcage directly under the bust. Key for supportive bikini tops.
Measure the narrowest point of your waist (natural waist), without sucking in.
Measure around hip bones. Useful for low-rise swim bottoms.
Measure around the fullest part of hips and buttocks with feet together.
Measure from shoulder (where strap sits) down through legs to crotch and back up. Key for one-pieces.
Alternative to torso length: shoulder-to-crotch-to-shoulder measurement for one-piece fit.
Measure around the fullest part of thigh for swim shorts and surf suits.
Universal Women’s Swimwear Size Chart (Most Common Baseline)
How to use this chart
This is a general baseline for swimwear sizing. Individual brands vary, so always cross-check with product-specific size charts when available. If you are between sizes: choose the smaller size for firmer compression, and the larger size for comfort and coverage.
| Size | US | UK | EU | Bust (in) | Waist (in) | Hips (in) | Bust (cm) | Waist (cm) | Hips (cm) |
|---|---|---|---|---|---|---|---|---|---|
| XS | 0-2 | 4-6 | 32-34 | 31-33 | 24-26 | 34-36 | 79-84 | 61-66 | 86-91 |
| S | 4-6 | 8-10 | 36-38 | 33-35 | 26-28 | 36-38 | 84-89 | 66-71 | 91-97 |
| M | 8-10 | 12-14 | 40-42 | 35-37 | 28-30 | 38-40 | 89-94 | 71-76 | 97-102 |
| L | 12-14 | 16-18 | 44-46 | 37-40 | 30-33 | 40-43 | 94-102 | 76-84 | 102-109 |
| XL | 16-18 | 20-22 | 48-50 | 40-43 | 33-36 | 43-46 | 102-109 | 84-91 | 109-117 |
| XXL | 20-22 | 24-26 | 52-54 | 43-46 | 36-39 | 46-49 | 109-117 | 91-99 | 117-124 |
| 3XL | 24-26 | 28-30 | 56-58 | 46-49 | 39-42 | 49-52 | 117-124 | 99-107 | 124-132 |
Swimwear Fabric & Stretch Rules (How Swimwear Actually Fits)
Why swimwear sizing feels different
Swimwear is designed to stretch. Most suits are made from nylon/polyamide or polyester blended with elastane/spandex. The more stretch and compression the fabric has, the more “snug” it will feel dry—and the better it usually performs in water.
| Fabric Type | Feel | Stretch & Recovery | Best For | Sizing Tip |
|---|---|---|---|---|
| High Compression (Power Mesh / Lined) | Firm & sculpting | High recovery | Tummy control, support | Between sizes: size up for comfort |
| Standard Stretch (Most suits) | Snug & flexible | Good recovery | Everyday swim | True to size usually works |
| Textured (Rib / Smocked / Crochet-look) | Thicker texture | Varies by knit | Trendy styles | Smocked can be forgiving; rib can run tight |
| Polyester Performance | Durable | Often firm | Pool, lap swim | May feel tighter dry; do not size down |
| Minimal Lining / Unlined | Lighter | More revealing | Sunbathing | If you want more coverage, choose lined styles |
Sizing Problems & Solutions (Quick Fix Boxes)
Fast diagnosis: size issue or style issue?
If a suit feels uncomfortable only in one area (bust, hips, torso), it’s usually a cut/style mismatch. If it feels uncomfortable everywhere, it’s usually the wrong size.
What it means: Cup is too big, straps are too long, or the cut doesn’t match breast shape.
- Adjust straps first (shorten) and tighten band if adjustable.
- Try a different cut: balconette, underwire, or molded cup.
- If gaping remains: size down in cup/overall top size.
What it means: Cup is too small or neckline is too open for your bust.
- Size up in cup/top size or choose fuller coverage.
- Pick underwire or bra-sized swim tops if available.
- Avoid tiny triangle tops for high activity or very full bust.
What it means: Band too loose, straps not supportive, or bandeau style lacks grip.
- Choose styles with back clasp, wider straps, or longline band.
- For bandeau: pick versions with silicone grip and removable straps.
- If it still moves: size down in band/top size.
What it means: Bottom is too small or leg/waist elastic is too firm.
- Size up in bottoms or choose tie-side/adjustable styles.
- Try softer-edge seams (no thick elastic) or higher-rise cuts.
- Avoid very low-rise if you prefer comfort at the hip.
What it means: Too small, too cheeky for your preference, or wrong leg cut.
- Choose more coverage: classic brief or hipster.
- Size up if fabric feels stretched thin over seat.
- Look for bottoms with a wider back panel and stable seams.
What it means: Waist is too small or the panel is too long/soft for your torso.
- Size up or pick a firmer, lined high-waist style.
- Try a mid-rise if you have a short torso.
- Look for styles with internal power mesh for stability.
What it means: Torso is too short for your body length.
- Choose long-torso sizing if offered.
- Try adjustable straps or tie-back one-pieces.
- If no long-torso option: size up and ensure bust/hip fit is still secure.
What it means: Torso is too long, or suit has too much fabric for your shape.
- Size down or try petite/short-torso fit.
- Choose styles with ruching or adjustable side ties to control fabric.
- Pick higher-compression fabrics for smoother fit.
What it means: Fabric is thin/unlined, especially in light colors.
- Choose lined swimwear or darker shades.
- Avoid very light unlined fabrics in white/cream/pastels.
- Textured ribbed fabrics can also improve opacity.
What it means: Wrong cup/band size or wire sitting on breast tissue.
- Ensure wire sits on ribs, not on breast tissue.
- Size up in cup or choose a different underwire shape.
- Try molded cups or supportive shelf-bra tops if you prefer no wire.
What it means: Seams/edges are rubbing due to tightness or cut placement.
- Choose flat seams, softer binding, or higher-quality lined construction.
- For halters: switch to straps that distribute weight (wide or cross-back).
- Consider swim shorts or skirted bottoms if inner-thigh rub is common.
What it means: Too large or too low-support for movement (especially waves).
- Choose sport tops, high-neck, longline, or zip-front styles.
- Pick bottoms with wider sides and secure seams.
- If you can pull it away from your body easily: size down.
One-Piece Swimsuits (All Types) — The Torso Length Master Rule
One-piece sizing priorities
- Priority 1: torso length (girth)
- Priority 2: bust and hips (largest measurement wins)
- Priority 3: support needs (underwire, cups, shelf bra)
| Style | Best For | Support Level | Torso Fit Note | Sizing Tip |
|---|---|---|---|---|
| Classic Scoop/Moderate | All body types | Medium | Standard torso | True to size; choose bigger if long torso |
| Plunge One-Piece | Elongating neckline | Medium | Needs stable straps | Full bust: choose cup-sized/underwire |
| High-Neck | Active movement | High | More coverage | Broad shoulders: check armhole comfort |
| Underwire / Cup-Sized | Full bust | High | More structured | Choose bra size chart when offered |
| Tummy Control / Shaping | Smoothing | High | Compression can feel shorter | Between sizes: size up for comfort |
| Swim Dress | More coverage | Medium | Skirt adds ease | Size by bust + torso first |
| Monokini / Cut-Out | Fashion-forward | Varies | Cut-outs affect tension | If in-between, size up to avoid digging |
| Athletic / Lap Suit | Swimming training | High | Firm fit by design | Do not size down; firm is normal |
| Surf Suit (zip/front) | Watersports | High | Torso length critical | Check shoulder width and bust fit |
Bikinis: Tops (Every Type) — Support, Coverage, and Shape
Top sizing priorities
- Support-driven tops: use underbust + bust (like bra logic).
- Triangle/string tops: use bust and coverage preference (more forgiving).
- If you have a fuller bust: prioritize adjustable bands, underwire, wider straps, and cup-sized options.
| Top Type | Support | Coverage | Best For | Fit Check |
|---|---|---|---|---|
| Triangle / String | Low–Medium | Adjustable | Small–medium bust, tanning | No side spillage, ties secure |
| Halter | Medium–High | Medium | Lift + classic | Neck tie not painful; band snug |
| Bandeau | Low–Medium | Medium | Tanning, minimal straps | No slipping; consider silicone grip |
| Underwire | High | Varies | Fuller bust | Wire sits on ribs, not tissue |
| Balconette/Demi | High | Open top | Lift + shape | No “quad-boob” or gaping |
| Full Cup | High | High | Maximum support | Encases tissue, stable straps |
| Longline | High | Medium | Extra stability | Band doesn’t roll; snug torso |
| High-Neck | Medium–High | High | Active, sporty | Armholes don’t chafe |
| Crop/Swim Top | Medium | High | Comfort, coverage | Hem stays down with movement |
Bikinis: Bottoms (Every Cut) — Rise, Coverage, and Leg Line
Bottom sizing priorities
Swim bottoms are primarily sized by full hips. Waist matters most for high-waist cuts. If you are between sizes and dislike digging: size up.
| Bottom Type | Rise | Coverage | Best For | Fit Check |
|---|---|---|---|---|
| Classic Bikini | Mid | Medium | Most body types | No hip digging |
| Hipster | Low–Mid | Medium | Lower-rise preference | Doesn’t roll down |
| High-Cut | Mid | Medium | Leg-lengthening | Leg opening not pinching |
| Cheeky | Mid | Less | Playful, modern | Stays centered, not shifting |
| Brazilian | Mid | Medium–Low | Curves emphasis | Back doesn’t ride too much |
| Thong | Low–Mid | Minimal | Tanning | No painful elastic |
| High-Waist | High | High | Coverage + shaping | Waist stays flat (no rolling) |
| V-Front | Mid | Medium | Flattering waistline | V sits flat without puckering |
| Tie-Side | Low–Mid | Adjustable | Flexible fit | Ties don’t dig, knots secure |
| Skirted Bottom | Mid | High | Extra coverage | Skirt lies flat, not flipping |
| Swim Shorts | Mid–High | High | Active/swim modesty | Leg opening doesn’t ride up |
| Boardshorts | Mid | High | Surf/watersports | Waist secure, not slipping |
Swimwear Care & Longevity (Keeps Fit and Color)
Care rules that prevent “bagging out”
Rinse immediately after swimming (pool or sea). Hand wash in cool water with gentle soap, avoid wringing, and dry flat in shade. Sunscreen and oils break down elastane—rinse sooner if used.
Your Perfect Swim Fit Starts Here
Measure bust, underbust, waist, hips, and torso length. Then choose: bikini tops by support needs, bottoms by hip and rise preference, and one-pieces by torso length + your largest measurement.
If you share your measurements, I can tell you the exact size you should list on your store for each swim category (one-piece, bikini tops, bikini bottoms, tankinis, and swim dresses).