Spandex (also sold as Lycra or elastane) is broken down by chlorine, so nylon-spandex suits stretch and go see-through faster in pools. Suits made of 100 percent polyester, or polyester with very little spandex, keep their shape far longer and are the standard choice for regular lap swimming and training. Rinse every suit in cool fresh water, do not wring it, and dry it flat out of the sun.
If you swim in a chlorinated pool more than once or twice a week, fabric is the biggest factor in how long your suit lasts.
Fabric compared
| Fabric | Stretch | Chlorine resistance | Best for |
|---|---|---|---|
| Nylon-spandex (Lycra, elastane) | High | Low | Occasional swims, beach, competition fit |
| Polyester-spandex blend | Medium | Medium | Mixed use |
| 100% polyester, PBT | Low to medium | High | Daily training |
Spandex gives stretch and a close fit, but chlorine, heat and sunscreen break it down. Polyester resists all three.
Reading the label
Look at the fiber content on the inside tag. A suit labeled “chlorine resistant” with 20 percent or more spandex will still degrade faster than a polyester suit. Brand names for long-life fabrics usually point to polyester constructions.
Cuts for training
- Women: thick-strap and closed-back cuts stay put during flip turns; thin-strap open backs give more shoulder freedom.
- Men: jammers (to just above the knee) and briefs are the training standards. Square-leg cuts sit between them.
See fit and sizing for brand size charts.
Care routine
- Rinse in cool fresh water right after swimming.
- Do not wring; press water out gently.
- Dry flat in the shade.
- Rotate two suits so each dries fully.
- Avoid hot tubs in your good suit.
For race day, a tech suit is a different item entirely; see tech suits explained. Pair your suit with goggles that seal using the goggle guide.
Browse swimwear.
Common questions
What is the most chlorine-resistant swimsuit fabric?
100 percent polyester, including PBT polyester. It has little or no spandex for chlorine to break down.
Why does my swimsuit go baggy?
Chlorine and heat break down spandex fibers. Hot tubs are especially hard on spandex.
Are polyester suits less comfortable?
They have less stretch, so they can feel firmer at first. Many swimmers prefer them for training and keep a softer suit for occasional swims.
Should I wash my swimsuit in a machine?
Hand-rinse in cool water after every swim. If you machine wash, use a mesh bag and cold water, and never put it in the dryer.