This custom swimwear sourcing guide covers everything you need to know.Swimwear is one of the most technically demanding categories in apparel. Unlike a t-shirt or running short, swimwear must withstand chlorine, saltwater, UV exposure, and repeated stretching — all while maintaining its shape, color, and fit.
For brands looking to source custom swimwear, the stakes are high. A swimsuit that fades, loses elasticity, or breaks down after a few wears will damage your brand’s reputation quickly. On the flip side, well-made swimwear creates loyal customers who return season after season.
This guide breaks down everything you need to know — from fabric choice to durability testing — so you can source swimwear your customers will love.
Why Swimwear Requires Special Fabrics — A Custom Swimwear Sourcing Guide
Swimwear is exposed to conditions that few other garments face:
| Challenge | What It Means for Fabric |
|---|---|
| Chlorine exposure | Chlorine in pools can degrade fabric fibers and cause fading |
| Saltwater | Salt can be abrasive and accelerate wear |
| UV exposure | Prolonged sun exposure can weaken and fade fabrics |
| Repeated stretching | Swimwear is stretched during wear — it must snap back to shape |
| Frequent washing | Swimwear is washed after every use. The fabric must survive repeated washing cycles |
Swimwear fabrics must be engineered to handle these challenges. Standard activewear fabrics won’t hold up.If you’re new to apparel manufacturing, start with our OEM vs ODM vs OBM guide to understand the different production models available for your brand.
Key Fabric Choices for Swimwear
Nylon-Spandex Blends — The Comfort Choice
Nylon is the most common fabric for high-quality swimwear. It’s soft, comfortable, and holds color well. When blended with spandex, it provides the stretch and recovery swimwear needs.
Why It Works:
- Soft against the skin: Feels smooth and comfortable
- Excellent color retention: Holds dye well, resists fading
- Good shape retention: Recovers well after stretching
- Durable: Resists pilling and abrasion
Recommended Blends:
| Blend Ratio | Best For | Key Characteristics |
|---|---|---|
| 80% Nylon + 20% Spandex | Performance swimwear | Maximum stretch and recovery |
| 82% Nylon + 18% Spandex | Everyday swimwear | Balanced comfort and durability |
| 85% Nylon + 15% Spandex | Light support styles | Softer feel, moderate stretch |
Polyester-Spandex Blends — The Durability Choice
Polyester swimwear is more chlorine-resistant than nylon and holds its shape even better. It’s the fabric of choice for competitive swimwear and high-durability applications.
Why It Works:
- Superior chlorine resistance: Outperforms nylon in chlorinated pools
- Excellent shape retention: Holds its shape over repeated use
- Quick-drying: Dries faster than nylon
- UV resistant: Holds up well under sun exposure
Trade-offs: Polyester swimwear can feel slightly less soft against the skin than nylon. It’s also less stretchy, so higher spandex content (typically 18-22%) is essential for comfort.
Best For: Performance swimwear, competitive swimsuits, and lines that emphasize durability. While nylon is often the preferred choice for comfort-focused lines, brands targeting pool-heavy use should consider starting with polyester-spandex for its superior longevity.
Spandex Content — The Stretch Factor
Spandex is critical in swimwear. Without enough spandex, the swimsuit will lose its shape. Too much, and it may feel too constricting.
Recommended Spandex Range:
22-25%: Maximum stretch, very compressive. Suits will feel very snug; may not be ideal for all body types or relaxed styles.
15-18%: Good for moderate stretch and recovery. Suits may feel more relaxed and hold their shape well with regular wear.
18-22%: Excellent stretch and recovery. The sweet spot for performance swimwear that needs to move with the body.
Understanding Fabric Weight and Stretch
Fabric Weight
Swimwear fabrics are typically lightweight. The right weight depends on the application:
| Weight Range | Feel | Best For |
|---|---|---|
| 160–180 gsm | Lightweight, very breathable | Swimwear that dries quickly and offers a barely-there feel |
| 180–200 gsm | Mid-weight, balanced | The sweet spot for most swimwear, offering durability without added weight |
| 200–230 gsm | Heavier, more durable | High-durability swimwear, competitive use, or styles with a more structured feel |
Four-Way Stretch
Swimwear requires four-way stretch — fabric that stretches in all directions, not just up and down. This allows the swimsuit to move with the body and return to its original shape.
What to look for:
- Stretch recovery: The fabric should return to its original shape after stretching — this is measured as a percentage of recovery after repeated stretching cycles
- Snap-back: After a full stretch, the fabric should snap back quickly without sagging
Testing tip: Stretch and recovery performance can vary significantly between fabrics with the same composition. When reviewing samples, ask the supplier for test data on stretch recovery, and test the fabric yourself by stretching it and observing how quickly and completely it returns to shape.
Chlorine Resistance
Chlorine resistance is one of the most important factors in swimwear durability. Chlorine degrades spandex over time, causing the fabric to lose elasticity and become loose.
How chlorine affects swimwear:
- Breaks down spandex fibers
- Causes fading and color loss
- Makes fabric stiff and brittle
- Reduces shape retention
What to look for in chlorine-resistant swimwear:
- Polyester-spandex blends: More chlorine-resistant than nylon-spandex
- Xtra Life Lycra: A specialized spandex fiber with enhanced chlorine resistance
- Test results: Ask your manufacturer for chlorine resistance test data
Expected lifespan: High-quality chlorine-resistant swimwear should maintain its shape and color for at least 100 hours of pool use.
UV Protection
Sun protection is increasingly important for swimwear customers — especially for children, outdoor swimmers, and beach vacationers.
UPF Rating:
| Rating | Protection Level | Best For |
|---|---|---|
| UPF 30+ | Good | Casual swimwear |
| UPF 40+ | Very Good | Beach and outdoor use |
| UPF 50+ | Excellent | Children’s swimwear, all-day sun exposure |
How to achieve UPF protection in swimwear:
- Dense fabric construction: Tight weave blocks more UV rays
- Darker colors: Absorb more UV than light colors
- UV-absorbing treatments: Chemical finishes that absorb UV radiation
Note: Wet fabric typically provides less UV protection than dry fabric. UPF claims should be based on wet testing for accuracy.
Design Features That Matter
Lining
Lining is essential for swimwear comfort and opacity. A well-designed lining system includes:
- Full body lining: Provides opacity and support
- Front lining only: Good for light colors and support where it matters most
- Powdered or seamless finishes: Reduces visible panty lines
Seam Construction
Swimwear seams must be stretchable and durable:
Bonded seams: Seamless appearance, ideal for minimal-coverage styles
Flatlock seams: Flat against the skin, reduces chafing
Overlock with elastic: Stretches with the fabric
Care and Durability
Helping your customers understand how to care for their swimwear can significantly extend its life:
Dry flat: Sunlight can cause fading and further fabric degradation
Rinse immediately: Rinse in cold water after use to remove chlorine, salt, and sand
Hand wash only: Machine washing can damage delicate swimwear fabrics and stretch out the garment
Avoid wringing: Wringing distorts the shape and damages the fibers
How to Source Swimwear for Your Brand
Quality Factors
| Factor | What to Check |
|---|---|
| Fabric test reports | Chlorine resistance, color fastness, tensile strength, stretch recovery |
| Sample quality | Fit, fabric feel, seam construction, print alignment |
| Color consistency | Dye lots should match your specifications |
| Certifications | OEKO-TEX or similar for chemical safety |
Commercial Factors
| Factor | What to Clarify |
|---|---|
| MOQ | Understand MOQ per style, color, and size |
| Lead time | Confirm production timeline and shipping |
| Sampling policy | Sample costs and process |
| Reordering | Lead times and MOQ for reorders |
Questions to Ask Your Supplier
“Can you provide samples before production?”
“What is your swimwear experience, and can you provide a portfolio of past work?”
“What fabric options do you offer for different use cases (chlorine resistance, UV protection, etc.)?”
“Can you provide test reports for chlorine resistance and color fastness?”
“What certifications do you hold?”
“What is your typical MOQ and lead time?”
For brands just starting out, our guide on how to start a custom sportswear brand with low MOQ provides additional tips and strategies for managing minimum order quantities.
Common Mistakes to Avoid
Mistake 1: Choosing Style Over Function
Design matters, but swimwear must perform. A beautiful suit that fades after three wears will hurt your brand more than a simpler design that lasts.
Mistake 2: Not Testing for Chlorine
If you’re making swimwear for pool use, chlorine resistance is non-negotiable. Test samples in chlorine water before approving bulk production.
Mistake 3: Overlooking Lining
Lining affects comfort, opacity, and how the swimsuit looks on the body. Consider lining as essential as the outer fabric.
Mistake 4: Ignoring UV Claims
If you make UV protection claims, test for them. Fabric density, color, and finishing methods all affect UPF ratings. Third-party testing ensures accuracy.
Quick Reference Checklist
Before placing your order, confirm these details with your manufacturer:
- □ Fabric composition matches your specifications
- □ Spandex content is confirmed (18-22% for performance)
- □ Fabric weight is confirmed (180-200 gsm is the sweet spot for most swimwear)
- □ Chlorine resistance is tested and documented
- □ UPF rating is tested (if claimed)
- □ Sample is approved before production
- □ MOQ and lead time are clear and documented
- □ Reorder process and pricing are confirmed
Why Work with JL Performance?
At JL Performance, we have experience sourcing swimwear with a focus on durability, comfort, and performance.
- Fabric expertise: We source from reputable mills and provide full test documentation
- Quality control: In-line inspections with third-party audits available
- Customization: From fabric to trims to packaging, we tailor to your brand
- Flexible MOQ: We support brands at every stage of growth
- Transparent communication: Clear timelines, clear pricing, and regular updates
Ready to source custom swimwear for your brand? Let’s talk. Contact us to discuss your requirements →
