Use the chart for the exact swimsuit model and market; an alpha or numeric label alone is not a reliable conversion across brands. TYR's adult swim charts map sizes against body measurements, while a Speedo Ocean Flex chart lists Speedo and U.S. sizes with bust, waist and hip ranges. Speedo also distinguishes recreational, training, open-water and racing fit, so start with the activity and cut as well as your measurements.
Swimsuit labels do not translate neatly from one maker or model to another. Start with the exact chart attached to the suit you are considering, then compare the measurements and fit guidance for the activity you swim.
Compare charts, not labels
| Chart example | What the maker lists | How to use it |
|---|---|---|
| TYR adult swim sizing | Alpha and numeric labels alongside body measurements; some performance charts include torso length | Match your current measurements to the chart for the suit type, not to a size remembered from a different cut |
| Speedo Ocean Flex one-piece | Speedo and U.S. sizes with bust, waist and hip ranges | Use the product page’s own chart and its measurement instructions for that model |
| Speedo activity guidance | Separate fit descriptions for recreational, training, open-water and racing suits | Choose the activity first; a deliberately compressive racing suit has different fit expectations from a recreational suit |
The TYR swim sizing chart shows how a label can sit beside several measurements. A Speedo Ocean Flex product page lists a model-specific chart with Speedo and U.S. size labels and bust, waist and hip ranges. These are examples of how two makers present size information, not a conversion between them.
Measure the way the chart asks
Use a soft tape and follow the exact maker’s instructions for each body point. Speedo advises measuring without pulling the tape tight, taking each measurement twice, and using the larger reading if the numbers differ. Its general size guide explains how it measures bust, waist, hip and chest.
Some one-piece charts also include torso length or a body-loop measurement. Those terms are not interchangeable: TYR includes a torso column in some swim charts, while Speedo defines body loop as a Fastskin-specific path from one shoulder down the front, through the crotch and back up to the same shoulder. Only measure it when the particular chart requires it.
Pick the fit for the activity
Speedo describes recreational suits as closer than everyday clothing while allowing movement, training suits as snug and supportive, open-water suits as secure at the arms and legs, and racing suits as compressive with their own sizing. Those are the maker’s fit descriptions; another brand can use different terms, so check its own guidance.
Once you have the chart size, check the suit’s cut and movement. Speedo’s fit checklist looks for fabric lying flat without gaps, straps staying in place, smooth leg openings and a full arm rotation without the suit pulling. Bunching, slipping straps, significant gaps or restricted arm movement are reasons to recheck the size and style.
Once size is settled, choose the cut that feels right for your session. Compare jammers, briefs and square-leg suits for men’s leg coverage and women’s training suit backs for strap layout and back coverage.
If a measurement falls between chart entries, do not automatically size up or down. Look for the maker’s model-specific advice and consider whether the suit is recreational, training or racing. For a different purchase decision, see our comparison of chlorine-resistant swimsuit fabrics and tech suits.
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Sources
Common questions
Can I use the same swimsuit size across brands?
Do not assume a shared size label means a shared fit. Compare your measurements with the chart for the exact brand, model, cut and market.
Which measurements should I take for a one-piece swimsuit?
Use the measurements named on the model's chart. Depending on the chart, those may include bust or chest, waist, hip and torso; do not add or substitute measurements that the maker does not request.
How tight should a training swimsuit feel?
Speedo describes its training fit as snug and supportive and says it can feel firm when dry. Check the product's activity and model-specific guidance, then make sure the suit allows a full arm rotation without pulling.
What does body loop mean on a swimsuit size chart?
Speedo defines body loop as a Fastskin-specific measurement from one shoulder down the front, through the crotch and up the back to that shoulder. Use it only when the exact chart calls for it.