The Best Supportive Swimsuits for Lap Swimming: What to Actually Look For
The best swimsuit for lap swimming is a full-coverage one-piece with a secure back design (like a crossover or racer back), firm-but-comfortable straps that won’t slip, and chlorine-resistant fabric that holds its shape lap after lap. Built-in shelf-bra support helps if you want extra security without wearing a separate bra. At Kozii, our Xover one-piece was designed specifically for this kind of swimming.
If you swim laps regularly, you already know the difference between a suit that helps you and one that fights you the whole way down the pool. Straps creeping off your shoulders, a neckline gaping on every tumble turn, fabric going baggy and see-through within weeks — these aren’t minor annoyances when you’re trying to get a workout in. Here’s how to choose a suit that disappears so you can focus on the swim.
What makes a swimsuit “supportive” for laps?
Support for lap swimming comes down to four things working together:
1. A secure back design
This is the most overlooked factor.
A crossover (Xover) back or racer back pulls the straps inward toward your spine so they physically can’t slide off your shoulders mid-stroke. Our Xover one-piece uses this exact principle; the crossover back holds you in and stays put through every lap. Thin, straight shoulder straps in a standard scoop back are the most likely to slip, especially during freestyle and backstroke.
2. Firm, wide-enough straps
Spaghetti straps might look great at the beach, but they tend to dig in and slip during repeated movement in the pool. Look for slightly wider straps, with structure and elasticity that holds shape under tension.
3. The right amount of compression
A lap suit should feel snug when you first put it on — it will relax slightly once it’s in the water.
Too loose, and it drags and fills with water. Too tight, and it restricts movement and breathing through your stroke.
4. Full coverage through the torso and bust
The more the suit holds everything in place, the less you think about adjusting it mid-swim.
Full coverage helps reduce movement, increases comfort, and improves focus during longer sets.
Why fabric matters more than you think
Pool chemicals are brutal on swimwear.
Standard fabrics break down quickly in chlorine — they fade, lose stretch, and become thin or baggy in high-stress areas like the bust and seat.
For lap swimming, look for chlorine-resistant (or chlorine-tough) fabric. It’s engineered to resist chemical breakdown so the suit keeps its shape, colour, and opacity for far longer.
Several styles in our full coverage range use chlorine-tough fabric for this reason; they’re designed to survive repeated weekly swimming without bagging out.
Cost note: Chlorine-resistant suits cost more upfront but usually last significantly longer, making them cheaper per swim than replacing lower-quality suits frequently.
One-piece vs two-piece for laps
For serious lap swimming, a one-piece almost always wins.
It keeps everything in place as a single system, removes the need for mid-swim adjustments, and prevents tops shifting during turns.
Two-pieces can work for casual swimming, but for uninterrupted lap sessions, a supportive one-piece is more reliable.
Do you need a shelf bra?
A shelf bra is an internal support layer that adds light shaping and security without a separate bra.
For lap swimming, it comes down to preference:
- Some swimmers like the extra support and structure
- Others prefer the compression of the suit alone
Several Kozii styles offer shelf-bra options so you can choose what feels best.
👉 Shop supportive swimsuits for larger busts
Caring for your lap suit so it lasts
Even the best fabric lasts longer with proper care:
- Rinse in cool fresh water immediately after swimming (don’t let chlorine sit in the fabric)
- Hand wash gently, avoid hot water, machines, and dryers
- Dry flat in the shade (avoid direct sun)
- Rotate two suits if you swim regularly so each gets time to recover
Why Kozii for lap swimming
Kozii has been designing swimwear for over 20 years in Tweed Heads on Bundjalung Country. Our suits are made from recycled fabrics, with chlorine-tough options built specifically for pool use and inclusive fit designs that support real bodies in real movement.
The Xover one-piece remains our most-loved lap style because it does exactly what a swim suit should do: hold you in, stay put, and get out of your way.
Frequently asked questions
What is the best swimsuit style for lap swimming?
A full-coverage one-piece with a crossover or racer back and chlorine-resistant fabric. The secure back stops straps slipping, and the tough fabric keeps the suit opaque and shape-holding over time.
Are chlorine-resistant swimsuits worth it for lap swimming?
Yes, they resist fading, stretching, and thinning caused by pool chemicals, making them more cost-effective over time.
How tight should a lap swimming costume be?
Snug but not restrictive. It should feel firm on land and relax slightly in the water. You should be able to breathe deeply and move through a full stroke without the fabric digging in.
How do I stop my swimsuit straps falling down when I swim?
Choose a crossover (Xover) or racer back. These pull the straps toward the centre of your back so they physically can't slide off your shoulders during freestyle or backstroke.
How long should a lap swimming swimsuit last?
A chlorine-resistant suit that's rinsed and cared for properly can last well over a year of regular swimming. A standard suit in chlorine often starts thinning and fading within a few months.