Jersey Fabric Guide: Single vs Double Knit, Stretch, and Sewing

1. Why Jersey Stretches: Loops vs Straight Threads

Unlike woven textiles where threads cross at rigid 90-degree angles, jersey fabric is knitted from a continuous series of interlocking loops.

When tension is applied, those curved yarn loops expand and flatten out, giving 100% cotton jersey 20% to 35% natural mechanical stretch even without adding any synthetic elastane or Lycra.

Calculate the weight of your t-shirt knits using our automated Fabric GSM Calculator.

2. Single Jersey vs Double Knit (Interlock)

• Single Jersey: Standard lightweight t-shirt material (140–180 GSM). Knitted with a single needle bed. The front displays vertical V-stitches, while the back displays horizontal wavy purl loops. The raw edges naturally curl when cut.
• Interlock (Double Knit): Knitted with two synchronized needle beds (200–260 GSM). Both sides of the fabric look identical, smooth, and flat. Raw cut edges lie completely flat without curling, making it much easier for beginners to sew.

3. Cotton vs. Modal vs. Poly-Spandex Jersey

The base fiber alters the drape and longevity of jersey:

• 100% Cotton Jersey: Breathable, structured, and absorbent. Ideal for casual, boxy t-shirts. Check our Cotton GSM Guide.
• Modal / Rayon Jersey: Exceptionally silky with liquid drape. Clings to curves and resists pilling, making it the favorite for feminine dresses and luxury sleepwear.
• Cotton-Spandex (95/5): Adds 5% elastane for complete recovery. Does not stretch out at the elbows or knees during movement. See our Fabric Blend Guide.

4. How to Calculate Fabric Stretch Percentage

Sewing patterns for knitwear specify a required "Stretch Percentage" (e.g., requires 50% crosswise stretch):

1. Fold your fabric crosswise and grip a 4-inch (10 cm) section between your thumbs.
2. Hold the left thumb at the 0 mark on a ruler, and pull the right thumb gently along the ruler until the fabric resists.
3. If the 4-inch section stretches comfortably to 6 inches, that is a 2-inch expansion: (2 ÷ 4) = 50% Stretch.

5. Essential Rules for Sewing Jersey at Home

Avoid wavy, popped seams with these adjustments:

• Always Use a Ballpoint or Stretch Needle (Size 75/11): Sharp needles puncture and sever the knitted loops, creating tiny run holes along seams after the first laundry wash. Ballpoint needles push loops aside safely.
• Never Use a Straight Stitch on Stretch Seams: Straight stitches have zero give. When the garment stretches to pull over your head, straight stitch threads will snap. Use a narrow zigzag stitch (0.5 mm width, 2.5 mm length) or a serger/overlocker.
• Do Not Pull While Feeding: Let the machine feed dogs pull the jersey forward naturally. Pulling while sewing stretches the seam permanently, creating an unsightly "lettuce-leaf" wavy ripple.

6. Taming Curling Raw Edges

Single jersey curls due to unbalanced yarn tension inside the knitted loops. To tame curling when cutting and pinning: spray the raw edges generously with wash-away liquid starch, press flat with a dry iron, and sew immediately. The starch washes out completely in the first rinse.