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Women's Swimwear Size & Fit Guide

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Women's Swimwear Fit Guide | Farnelli Fit Lab

Women's Swimwear Fit Guide

Swimwear should feel secure, comfortable, and confidence-boosting. We make it simple: pick your size system, choose your numbers, and we guide you to the best starting fit and swimwear styles.

Smart Start

Tell us what you want. We will take you there right away. Pick one box below.

I want my swimwear size (fast)

Choose your size system (US/UK/EU) and your measurements. We suggest a safe starting size.

I want the right swimwear style

Use filters. We explain every swimwear style in simple words.

I want a flattering shape

We help you pick a swimwear shape that feels balanced and looks amazing.

I want support (I need to move!)

We show the best fabrics, fits, and simple tricks to feel secure in the water and on the beach.

I don’t know anything (help me)

The fastest path (3 steps)
1) Measure bust 2) Measure waist 3) Measure hips Then pick a swimwear style
Simple checklist
  • You measured bust, waist, and hips.
  • Your tape was snug, not tight.
  • If you are between sizes: for swimwear, decide your feel (snug/secure = smaller, more room = bigger).

If something feels off, go to Fixes. We tell you exactly what to change.

Size Finder
Swimwear sizing (super simple)
  • Bust is the fullest part of your chest.
  • Waist is the smallest part of your middle.
  • Hips is the fullest part of your hips/seat.

Swimwear should feel secure (it will relax a little in water). If you are between sizes, pick your goal: secure = smaller, more coverage/room = bigger.

1) Pick system 2) Pick bust 3) Pick waist 4) Pick hips 5) Tap button

Option A: Use measurements (best)






No tape measure?

Use a string. Wrap, mark it, then measure that length with a ruler.

Option B: I know my regular size already

Pick your everyday size system and size. We show the closest match + all conversions (Alpha / US / UK / EU / IT / FR / AU).



Swimwear fit rule

If your bust/waist/hips are in different sizes, pick the size that fits the largest area for a secure fit, or choose an adjustable style (ties, straps, wrap).

Fit Rules

The 6 easy swimwear fit rules

  • It must stay put: move your arms, bend, and walk—no constant adjusting.
  • Band/underbust should be secure: snug is good, pain is not.
  • Cups should lie smooth: no gaping, no major spillage.
  • Bottoms should not dig: gentle hug, not a hard cut-in.
  • Coverage check: sit down and do a small squat—make sure you feel covered.
  • Wet fit matters: swim fabrics relax slightly in water—secure dry fit is important.
Between sizes = secure vs roomy Adjustable ties help Wet fit relaxes

How to measure (super easy)

Bust
Tape around the fullest part of your chest. Keep it level.
Waist
Tape around the smallest part of your waist. Snug, not tight.
Hips
Tape around the fullest part of your hips/seat. Keep it level.
Wear the right base
Measure over thin clothes or underwear. Thick clothes change numbers.

Find Your Swimwear Style

All-inclusive list of women’s swimwear styles. Use filters to find your vibe and the easiest, most secure fit.

Classic One-Piece

One-piece swimsuit with secure coverage. Great balance of comfort and confidence.

SecureFlatteringEasy pick

Triangle Bikini

Adjustable triangle top (ties/straps). Great for tanning and easy sizing.

AdjustableTanningLight support

Bandeau Bikini

Strapless top for minimal tan lines. Best with grip/boning for security.

No strapsTan linesSecure fit matters

High-Waist Bikini

Higher-rise bottoms for more tummy coverage and a vintage silhouette.

More coverageVintage vibeFlattering

Halter Top

Straps tie/fasten behind the neck. Great lift; check neck comfort for long wear.

LiftSecureNeck strap

Tankini Set

Two-piece with more coverage on the torso. Easy bathroom breaks + flexible sizing.

More coveragePracticalEasy fit

Monokini / Cut-Out One-Piece

One-piece with strategic cut-outs. Bold look; fit must feel secure when moving.

StatementBoldSecure fit

Rash Guard / Surf Top

More coverage and sun protection. Best for surfing, water sports, or modest coverage.

UPF-friendlyActiveCoverage

Swim Shorts / Boyshort Bottoms

More coverage at the leg and seat. Great for active swimming and comfort.

ActiveComfortCoverage

Swim Skirt / Swim Dress

Built-in bottoms with a skirted layer. Great if you want extra coverage.

Extra coverageComfortClassic

Ruched / Tummy-Control Styles

Gathering or shaping panels that feel forgiving at the tummy and look very flattering.

ForgivingFlatteringConfidence

Underwire / Bra-Sized Tops

More lift and shape. Best for support and a secure feel.

SupportLiftSecure

High-Leg / Cheeky Cuts

Higher leg opening or cheekier back for a longer-leg look. Coverage is less—choose what feels you.

Leg-lengtheningSexyLess coverage

Full Coverage / Modest Cuts

More coverage at the bust and bottom. Great for comfort, family trips, and active swimming.

CoverageComfortActive-friendly
Safe pick

If you are unsure: choose a classic one-piece or a high-waist bikini. They are flattering, comfortable, and easy to wear.

Find Your Swimwear Neckline

Necklines change the vibe and the support. Answer 3 quick questions and we suggest the best swimwear necklines to start with.

Sweetheart
Heart-shaped top edge. Romantic and flattering, often paired with structured cups.
Strapless / Bandeau
No straps. Best with grip/boning for security—especially for swimming.
Off-Shoulder
Sleeves sit below shoulders. Pretty and resort-ready; check movement comfort.
V-Neck
Elongates the neckline. Great for one-pieces and supportive bikini tops.
Scoop / Round
Simple and sporty. Comfortable and easy for most activities.
Square
Clean lines. Modern and secure-feeling with straps or wide banding.
Halter
Fastens behind the neck. Great lift; test neck comfort for long wear.
High Neck
More coverage up top. Great for sporty looks, surf tops, and extra security.
Plunge
Deep V. Bold and glam—best with secure structure or supportive underband.
Bateau
Wide and high. Elegant, more coverage, often very secure with straps.
One-Shoulder
Fashion-forward and clean. Great for pool looks; check strap stability.
Keyhole
Small opening detail. Adds interest while keeping coverage and support.

Find Your Swimwear Fabrics

Fabrics decide the feel: soft vs compressive, quick-dry vs textured, smooth vs ribbed. Answer 3 quick questions and we suggest swimwear fabrics to start with.

Everyday swim fabrics (most common)

  • Nylon + spandex: smooth, stretchy, quick-dry (the classic).
  • Polyester + spandex: durable and often very chlorine-friendly.
  • Double-lined fabric: more coverage, more support, less see-through.

Support + shaping

  • Compression knit: firmer hold, feels secure.
  • Power mesh lining: hidden support panels for tummy/waist.
  • Ribbed knit: texture with a supportive feel (varies by thickness).

Textured / statement

  • Ribbed: trendy texture, often flattering.
  • Smocked: stretchy and forgiving, casual-cute.
  • Crochet-look: resort vibe (usually lined—check comfort and support).

Comfort tips

  • For swimming laps: choose durable, secure fabrics (often polyester blends).
  • For strong sun: consider UPF coverage pieces (rash guards, surf tops).
  • For the smoothest look: choose double-lined, compressive fabrics.

Details That Matter
Adjustability (ties / sliders)
Adjustable straps and ties help you fine-tune fit (great if you are between sizes).
Double lining
Adds coverage and support. Often feels more secure and less see-through.
Underwire / molded cups
More shape and lift. Great for support; make sure it doesn’t dig.
Removable padding
Optional shape. If it shifts, you may prefer sewn-in or molded cups.
Bottom coverage
Cheeky, moderate, full. Choose what feels comfortable for walking and sitting.
Leg cut
High leg elongates; lower leg cut gives more coverage. Pick your comfort.

Fixes

Pick your issue. We tell you what to do.

Top feels loose / not secure
Size down or choose a more supportive style (underwire, wide band, adjustable straps). Strapless needs extra security.
Top is digging / too tight
Size up or choose softer elastic / adjustable straps. Pain is never the goal.
Bottoms dig at the hips
Try a larger size, a different cut (higher rise, wider sides), or a softer elastic edge.
Bottoms slip / feel loose
Size down or choose a style with more hold (compression, wider waistband, tie sides).
One-piece rides up
You may need a longer torso fit, adjustable straps, or a slightly bigger size for length.
Coverage feels too revealing
Choose fuller coverage bottoms, swim shorts, tankini, rash guard, or a swim skirt/dress layer.
Fabric shows lines
Choose double-lined or textured fabrics (ribbed, ruched) and ensure a smooth, secure fit.

FAQ
Should swimwear feel tighter than normal clothes?
Yes—slightly. Swim fabric relaxes a bit in water. It should feel secure, not painful.
What if bust/waist/hips are different sizes?
Choose the size that fits the largest area for security, or pick adjustable styles (ties, straps, wrap tops).
What is the safest swimwear style?
A classic one-piece, or a high-waist bikini with adjustable straps. Secure and flattering.
Do I need padding or underwire?
Not required. If you want more lift/shape, underwire or molded cups help. Comfort first.

Glossary

Small dictionary. Search a word here.

One-Piece

A swimsuit that is one connected piece. Usually secure and easy to wear.

StyleEasy

Bikini

A two-piece swimsuit (top + bottom). Many fits: adjustable, supportive, or minimal.

StyleEasy

High-Waist

Bottoms with a higher rise. More coverage and often a vintage look.

StyleEasy

Double-Lined

Two layers of fabric. More coverage, more support, and less see-through.

DetailsEasy

Underwire

A wire under the cup for lift and shape. Adds support when it fits correctly.

DetailsEasy

Ruching

Gathered fabric texture. Often feels forgiving and flattering.

DetailsEasy

Nylon + Spandex

A common swim blend. Smooth, stretchy, and quick-drying.

FabricEasy

Compression

Firmer fabric that holds you in for a secure feel and smoother look.

FabricEasy

Coverage

How much skin a suit shows (cheeky, moderate, full). Choose what feels comfortable for you.

FitEasy

Size Conversions

How one size system maps to another (Alpha / US / UK / EU / IT / FR / AU). Use it when shopping internationally.

FitEasy
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