Racing Swimsuit Size Guide: How a Jammer or Kneeskin Should Fit
Last updated: October 2026 · By the Aqua Style team
A racing swimsuit should feel very tight on dry land: firm compression with no loose fabric, no wrinkles at the hips and no gaps at the legs, while you can still breathe deeply and raise your arms. Racing jammers and kneeskins are cut smaller than training suits, so most swimmers use the brand's racing size chart rather than their everyday size.
Racing suit vs training suit
| Training suit | Racing suit (tech suit) | |
|---|---|---|
| Fit | Snug but relaxed | Compressive, much tighter |
| Fabric | Chlorine-resistant, built for daily use | Lightweight, water-repellent, built for speed |
| Use | Every session | Races and key fast sets only |
| Putting on | Seconds | Often 10 minutes or more |
How to choose your size
- Measure your waist and hips for a jammer; chest, waist, hips and torso length for a women's kneeskin.
- Use the brand's racing chart. Each brand sizes differently. Use the Arena men's and women's racing charts, the TYR men's and women's racing charts, and the Mad Wave men's racing chart and women's racing chart.
- Between two sizes? Experienced racers usually choose the smaller size. First-time tech-suit buyers and growing juniors are often more comfortable in the larger one.
Putting on a tech suit without damage
- Remove rings and keep fingernails short. Pull the fabric with the pads of your fingers, never your nails.
- Roll the suit up your legs a little at a time instead of pulling from the top.
- Wear a thin plastic bag over your foot while sliding the leg on, then remove it.
- Only use the suit for races and race-pace practice. Daily training wears it out quickly.
Competition rules in brief
For events held under World Aquatics rules, racing suits must be on the approved list. Men's suits may not go above the navel or below the knee, and women's suits may not cover the neck, extend past the shoulders or go below the knee. Approved suits usually carry an approval mark; product pages such as the Mad Wave Revolt racing jammer state this. Always confirm the rules of your specific event.
Frequently asked questions
Should a racing jammer be tighter than a training jammer?
Yes. A racing jammer should feel noticeably tighter, with no wrinkles or loose fabric. If it feels as relaxed as your training suit, it is probably a size too big.
Can a racing suit be returned after trying it on?
For hygiene reasons, swimwear cannot be returned once opened or worn, as set out in our return policy. Measure carefully, check the chart and contact our team before you open the pack if you are unsure.
How long does a racing suit last?
Tech suits give their best performance for a limited number of races. Rinsing in cool fresh water and drying in the shade after every use keeps the fabric and compression working longer.
Shop men's racing swimsuits and women's racing swimsuits, or message our team for help with sizing.
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