Elastic Guide: Choosing the Right Type & Width for Your Sewing Projects

Article published at: Apr 19, 2026 Article author: Fabric Team Article tag: backpack sewing pattern
Elastic Guide: Choosing the Right Type & Width for Your Sewing Projects - Fabric + Flow Textile Co.
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Elastic Guide: Choosing the Right Type & Width for Your Sewing Projects

Elastic might seem like a small detail — but it can completely make or break your project.

The right elastic gives your garment structure, support, and longevity. The wrong one? It can stretch out, twist, or lose shape after just a few wears.

If you’ve ever felt unsure about which elastic to use, this guide breaks it all down — simply and clearly.

The Most Common Types of Elastic

Knit Elastic

Best for: Everyday garments, waistbands, light stretch projects

Knit elastic is soft, flexible, and easy to work with — making it a popular choice for beginners. We have it in white and black.

Why you’d use it:

  • Doesn’t narrow as much when stretched

  • Comfortable against the skin

  • Great for waistbands in loungewear or casual garments

Keep in mind:
It’s not designed for high tension or long-term exposure to water, chlorine, or sun.

Braided Elastic

Best for: Casings in underwear, swimwear, or sportswear

Braided elastic is made from tightly woven fibres in a rope-like braid. Unlike knit elastic, it narrows as you stretch it, which can cause puckering or twisting if sewn flat.

Why you’d use it:

  • Holds strong in lengthwise stretch
  • Perfect for enclosed casings where the fabric protects it

Tip: For most exposed swim edges, rubber elastic is still the preferred choice due to its superior hold, water resistance, and recovery.

Non-Roll Elastic 

Best for: Structured waistbands, areas that need stability

Non-roll elastic is firmer and holds its shape really well.

Why you’d use it:

  • Prevents twisting inside casings

  • Great for thicker waistbands

  • Adds structure to garments

Keep in mind:
It’s less flexible than knit elastic, so it’s not ideal for projects that need a lot of stretch and recovery.

Clear Elastic

Best for: Stabilizing seams, lightweight stretch fabrics

Clear elastic is thin, transparent, and often used behind the scenes.

Why you’d use it:

  • Stabilizes shoulder seams

  • Adds light support without bulk

  • Great for delicate or sheer fabrics

Keep in mind:
It’s not strong enough to act as the main support elastic in garments like swimwear.

Rubber Elastic (Swim Elastic)

Best for: Swimwear, activewear, high-performance garments

This is the go-to elastic for anything that needs to withstand water, movement, and repeated wear.

Why rubber elastic is best for swim:

  • Chlorine + saltwater resistant → won’t break down like knit elastic

  • Superior recovery → snaps back into shape even after heavy use

  • Stronger hold → keeps suits secure without sagging

  • Durability → made to handle sun, water, and stretching

Unlike knit elastic, which can lose elasticity and become “wavy” over time in swim, rubber elastic is designed specifically for these conditions — which is why it’s essential for a long-lasting swimsuit.

Common Elastic Widths & When to Use Them

Choosing the right width is just as important as the type.

6–8mm (¼”–⅜”)

  • Leg openings in swimwear

  • Necklines and armholes

  • Lightweight, subtle finishes

10–12mm (⅜”–½”)

  • Light support areas

  • Bralettes or soft tops

  • Some swim applications

19mm (¾”)

  • Waistbands

  • Underbust bands

  • Areas needing more hold and structure

Common Mistakes to Avoid

Using knit elastic for swimwear
It might seem easier to sew, but it won’t hold up over time in water.

Choosing the wrong width
Too wide = bulky seams
Too narrow = not enough support

Stretching elastic too much while sewing
This can cause puckering or overly tight edges. Aim for consistent, controlled tension.

Final Thoughts

Elastic isn’t just a finishing detail — it’s a core part of how your garment fits, feels, and lasts.

Once you understand the differences, choosing the right elastic becomes second nature — and your projects instantly look and perform better.

And when it comes to swimwear? Rubber elastic is always the way to go.

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