Finding the right plus size sportswear supplier is a critical step for any sportswear brand aiming to serve the rapidly growing and underserved plus size market. Yet, it’s not just about choosing a sportswear supplier with the right production capacity. To truly deliver high-quality, flattering, and functional garments for plus size consumers, you need to dive much deeper into pattern grading, fabric sourcing, and garment construction knowledge.
In this post, we’ll walk you through what makes a great plus size sportswear supplier, why standard sizing fails larger bodies, and why fabric choice is arguably just as important as your design. Whether you’re starting a new activewear brand or expanding into inclusive sizing, these insights will, help you build a line that your target market will love and trust.
At Blue Associates Sportswear, we have designed and developed several plus size ranges for our clients, from size 6 up to size 30 and this knowledge has led us to understand the requirements and investment required to produce a plus size collection.
1. Why Standard Grading Fails in Plus Size Sportswear
One of the biggest mistakes new brands make is assuming they can simply scale up smaller sizes to create plus size garments. This process—known as standard grading—might work for a straight-size range (XS–XL), but it often fails dramatically when applied to sizes XL and above.
Here’s why: Bodies don’t scale proportionally.
A size 20 woman may have the same bust as a size 12, but a shorter torso, or carry weight in different places (like hips or arms). Height does not increase with size—plus size individuals could possibly be shorter in stature, meaning longer leg inseams and torsos can lead to poor fit, bunching, and discomfort.
Instead, true plus size sportswear needs dedicated pattern development that respects and reflects the nuances of larger bodies. This requires a designer and supplier with experience in plus size product development—not just someone who claims to manufacture a wider range of sizes.
Features, seams and detailing also need to be considered. On size S-XL garments, the trims, labels and logos are usually standardised across the sizes, however a label or trim detail on a size S may look great, but needs to be scaled on garments over XXXXL+ so they stay in proportion to the overall garment.
2. The Factory Builds the Garment. They Don’t Produce the Fabrics, Trims and Components
A common misconception among new activewear brands is that the supplier or factory handles everything, from fabric to labels to trims. But in reality, the factory is like a builder of a house—they simply construct the garment based on the materials you provide or nominate.
That means:
- You’re responsible for sourcing or nominating the fabric
- The same goes for zippers, elastics, drawcords, waistbands, and even hangtags.
- If you don’t specify the quality or supplier of a fabric or trim, the manufacturer may substitute something cheaper, which can affect performance and brand reputation.
Also note that if you leave this up to the factory to source, you have no idea where this fabric or trim came from and what the performance and quality is like. It also makes it impossible for you to move to another factory and produce exactly the same quality.
All established brands source and nominate fabrics, trims and components so they are in full control of the quality and performance.
Understanding CMT vs. Full Package Production
If your goal is premium plus size activewear, it’s crucial to partner with a factory experienced in working with nominated suppliers and premium performance fabrics. You should also ensure that your team (or your tech pack creator) understands the full bill of materials (BOM) so no detail is left to chance.
Nearly every freelance designer that doesn’t manage the production and sourcing doesn’t nominate the fabrics and trims as they lack the knowledge and contacts. At Blue Associates Sportswear, we receive so many designs and tech packs from start ups without fabric and trim information, requesting the factory to source. This is basically the same as asking your builder to select your tiles!
3. Why Sourcing and Nominating Fabrics and Trims Is Crucial
In plus size sportswear, the materials make or break the product. You could have the best pattern and the most ethical factory, but if your fabric doesn’t perform—or worse, becomes see-through when stretched—it can destroy customer trust instantly.
This is why nominating specific fabrics and trims is a must. You control the input; the supplier controls the output. Here’s what that typically involves:
- Choosing technical fabrics that have the right blend of stretch, recovery, power, moisture-wicking, and opacity.
- Ensuring your elastics or waistbands offer strong hold without rolling or digging in.
- Selecting high-quality stitching thread that can withstand wear and stretch without breaking.
- Including labels and trims that are soft, non-abrasive, and won’t cause chafing. (Remember to scale these to the grade of the patterns)
You also need to test fabric performance in advance through swatch sampling and prototype fitting—ideally on actual plus size fit models. Not all stretch fabrics are created equal, especially when stretched over curves. That brings us to the next critical point…
4. Fabric Choice Matters: Flattering and Squat-Proof Are Non-Negotiables
If you’re designing leggings or any tight-fitting athletic garment, your customers will expect the fabric to be squat-proof—meaning it doesn’t become see-through when they bend or stretch. This is particularly critical for plus size leggings, where more fabric is required to accommodate curves, which can stretch fabric more significantly.
Here’s what to look for in squat-proof, plus size-friendly fabric:
- High GSM (grams per square meter): Heavier-weight fabrics often provide more coverage.
- Four-way stretch with strong recovery: So the garment doesn’t bag out after wear.
- Nylon-spandex blends are often superior to polyester for softness and durability.
- Brushed finishes help reduce shine and make the fabric feel softer against the skin.
Also, not all compression is good compression. Too much tightness can cause bulging or restrict movement and blood flow, especially in the waist, thighs, and calves. You need fabrics that offer a balance of support and breathability—and ones that move with the body, not against it.
Lastly, think about aesthetics. Shine, texture, and drape can affect whether a garment looks slimming or bulky. Fabrics with matte finishes and strategic seam placements can be more flattering, especially when designed specifically for curves.
Colour is also a great tool to use to create more flattering products. Pale colours can look great on smaller sizes but emphasise size when scaled up. Darker shades typically slim and disguise lumps and bumps.
How to Evaluate a Plus Size Sportswear Supplier
Now that you understand why fabric choice, pattern development, and material nomination matter, let’s look at how to vet your potential suppliers. Here’s a checklist:
Look for Suppliers With:
- Experience in plus size activewear production
- A track record of working with international brands or technical garments
- A library of fit-tested plus size blocks or willingness to develop custom ones
- Strong communication and sampling process
- Openness to working with nominated fabric mills and trim suppliers
- Experience with performance testing and quality control
- Experience in sourcing suitable fabrics and trims
If you’re not sure where to start, platforms like Common Objective and Maker’s Row can help you discover ethical and experienced garment suppliers. Remember though that you are simply talking to the builder here. You need to supply your builder with a complete tech pack and make sure this nominated the fabrics and trim suppliers.
Bonus Tips for Brands Entering the Plus Size Market
Entering the plus size market is a powerful move, but it comes with responsibility. Here are a few things to keep in mind:
- Don’t stop at size XL. A truly inclusive brand should offer sizes up to at least 6X (and ideally more).
- Use fit suitable PLUS SIZE models during sampling to catch issues early.
- Avoid labelling anything “flattering” unless you’ve tested it with your audience and can back it up.
- Don’t use straight-size models in plus size product shots—your customers will notice.
- Include plus size people in your design and testing process from day one.
Creating exceptional plus size sportswear isn’t as simple as increasing pattern dimensions or picking stretchy fabric. It requires intentional design, collaboration with the right supplier, and careful sourcing of each material component.
The best suppliers are partners, not just manufacturers. They’ll help you bring your vision to life—but it’s up to you to provide the blueprint, fabric choices, and a clear understanding of your target customer’s needs.
Want to dig deeper into how to build a truly inclusive activewear brand? Check out our guide on How to Launch a Sustainable Activewear Line for even more insights on ethical sourcing and long-term brand growth.
If you’re ready to start sourcing or need help with tech packs, fabric selection, or fit testing, we can help. Contact us for expert support in building your plus size activewear collection.