How to Measure for a Swimsuit (One-Piece, Bikini, Swim Trunks)
Swimwear is the highest-return apparel category online — usually because of one missing measurement: torso length. Here's how to take all five swimwear-relevant numbers and pick the right cut for each style.
Swimwear sizing is the only category where four measurements isn't enough. You need bust, waist, hips — and for one-pieces, you need torso length, the silent measurement that decides whether the suit rides up your hips, sags off your shoulders, or sits clean. For men's swim trunks, the silent measurement is inseam: 5", 7", 9", or 11" boardshort length.
Take all the numbers once and swimwear shopping stops being a guessing game.
Step-by-Step: Women's Swimwear Measurements
- Bust. Tape around the fullest part of the bust, parallel to floor, snug not compressed. Wear a non-padded bra or none. See our bust measurement guide.
- Waist. At your natural waist (narrowest point above the navel). Tape parallel to floor, snug. See our waist measurement guide.
- Hips. Around the fullest part of your hips and seat — usually 7–9 inches below natural waist. Stand with feet together. See our hip measurement guide.
- Torso length (one-piece only). Place the start of the tape on the highest point of your shoulder. Run it down the front of your body, between your legs (snug against the crotch), and back up the spine to the same shoulder point. The total is your torso length.
- Underbust (bikini top with cup, optional). If buying a bikini top with cup sizing (D+), measure underbust like a regular bra. See our sports bra measurement guide for the technique.
Why Torso Length Matters
The single fix that solves most swimsuit returns
| Height range | Average torso length | Typical cut to look for |
|---|---|---|
| ≤5'2" (petite) | 55–58" | Short torso / petite cut |
| 5'3"–5'5" | 57–60" | Regular cut |
| 5'6"–5'8" | 60–63" | Regular cut (toward long) |
| 5'9"+ | 63–67" | Long torso / tall cut |
If your measured torso falls outside your typical-height range, you have an unusually long or short torso for your height — and a "regular" suit will likely fit wrong. Brands like Speedo and TYR offer explicit long-torso cuts; Lands' End offers both long-torso and short-torso variants.
Step-by-Step: Men's Swim Trunks Measurements
- Waist. Trunks size by waist in inches (same as regular shorts). Tape at where the trunks will sit — usually 1–2 inches below the natural waist (low-rise) or at the natural waist (high-rise).
- Inseam. Measure from the crotch seam down the inside of the leg to where you want the hem to end. Or use a pair of trunks you like as reference: lay them flat, measure inseam from crotch seam to hem.
- Hip / seat (optional). If you're between waist sizes or have an athletic build, measure hips at the fullest point. Some athletic-cut trunks list this on the chart.
| Inseam | Style | Best for |
|---|---|---|
| 5" | Short trunks / running short | Pool / casual / pre-2010 retro |
| 7" | Standard trunks | Beach / pool / most uses |
| 9" | Mid-length boardshorts | Surfing, watersports, modesty preference |
| 11" | Long boardshorts | Surfing, sun protection, cargo-style |
| 13"+ | Knee-length boardshorts | Sun-protective swim, older / conservative cut |
Cut and Coverage — Bottoms
Brief / regular bottom (women)
Hipster / mid-rise bottom
High-waisted bottom (retro)
String / tie-side
Cheeky / Brazilian
Boyshort
Cut and Coverage — Tops
Triangle
Bandeau
Halter
Bralette / soft cup
Underwire / structured
Tankini
Common Mistakes
Skipping torso length on a one-piece
Bust/waist/hips alone don't tell the brand whether you have a 56" or 65" torso. The same suit fits both — wrong on one of them.
Buying bikini tops by S/M/L when you're D+
S/M/L bikini tops fit up to roughly C cup well. D+ needs cup-and-band sizing or "fuller bust" labels.
Using your dry-fit feel to evaluate a suit
Swimwear loosens 5–10% wet. A dry fit that feels "snug-but-comfortable" is right. A dry fit that feels "barely-snug" will sag wet.
Ignoring leg-cut height on bottoms
A high-cut leg on a low-hip-curve body cuts in. A low-cut leg on a high-hip-curve body looks dated. Match leg cut to your hip-to-waist ratio, not just hip measurement.
FAQs
How do I measure for a one-piece swimsuit?
Bust, waist, hips, plus torso length (shoulder, down front, between legs, up back). Torso is the unique swimwear measurement.
What is torso length and why does it matter?
Torso length is total vertical fabric needed to cover your torso. Wrong torso = suit rides up or sags.
How should swimwear fit?
Snug but not constricting. Stretches when wet, so dry fit should be slightly closer than you'd ideally like.
Should I size up or down for swim trunks?
Buy your standard waist size in inches. Pick inseam by style: 5–6" short, 7–8" standard, 9–11" boardshort.
Why does my swimsuit ride up?
Usually torso too short for body, hip too small, or leg cut too high. Long-torso cut or hip-up-size fixes most cases.
Are bikini tops sized like bras?
D+ tops use band-cup. S/M/L tops fit best up to about C cup.
Swimwear Sizing Doesn't Have to Be Roulette
The five-minute torso measurement is what separates "buy three sizes and return two" from "buy one and keep it." Take it once and swimwear shopping stops being a vacation chore.
For more category-specific reference, see our bra size chart (bikini cup sizing), women's dress size chart (general sizing reference), and men's pants size chart (waist sizing for swim trunks).
Selling swimwear on Shopify? Returns can be 50%+ without proper sizing.
Tailor Size Guide adds torso length and cup-by-band sizing to every swim listing so customers find their actual fit before ordering.