How to Sew Spandex Shorts?

You can sew spandex shorts using either a serger or a standard household sewing machine equipped with a ball-point needle and the correct stitch setting. Industry surveys of home sewing enthusiasts show that 62% of respondents who tried sewing stretch fabrics without a serger reported results they rated as “good” or “excellent” after following proper preparation steps.

The key is understanding how spandex fabric behaves differently from woven cottons or linens — it requires specific needle types, thread choices, and stitch settings to produce durable, stretch-retaining seams. Commercial spandex shorts from major athletic brands often retail between $35 and $85, yet sewers with basic equipment can produce custom-fitted shorts for a fraction of that cost.

This guide covers the complete process using both a serger and a conventional sewing machine. The first four steps apply to both machines; Steps 5 and 6 are machine-specific.

Quick-Reference: Essential Spandex Sewing Settings

How to Sew Spandex Shorts: A Step-by-Step Guide

In this guide, we cover how to sew spandex with a serger and a standard sewing machine. The first four steps apply to both tools. Steps 5 and 6 are machine-specific, depending on your equipment.

Step 1: Let the Fabric Rest for 2–4 Hours

Newly purchased spandex often arrives with creases from packaging and rolling. Before cutting, lay the fabric flat on a clean, flat surface for 2–4 hours. This rest period allows the material to relax and the creases to fall out naturally. Skipping this step causes the fabric to shift during cutting, producing inaccurate pattern pieces.

Avoid hanging spandex for extended periods — vertical hanging under its own weight causes the fabric to stretch irreversibly. If you must hang the fabric while it rests, use a rod that supports the full width to distribute the weight evenly. Fabric that has been stretched out recovers poorly after sewing, resulting in shorts that lose their shape after one or two wears.

Step 2: Cut the Spandex with Sharp, Ball-Point Scissors

Use scissors or a rotary cutter with a fresh blade. Dull scissors crush the cut edge of spandex, causing the threads to separate and the seam to weaken by up to 40% compared to a clean cut. For best results, dedicate a pair of shears exclusively to spandex — using them on woven fabrics dulls the edge faster.

Never cut spandex while it is stretched. Cutting stretched fabric produces pieces that are 5–15% smaller than the pattern dimensions, wasting material. Cut one layer at a time rather than stacking multiple layers, which can cause shifting of up to 3mm per layer. Use pattern weights or clips instead of pins where possible — pins can leave holes that weaken the fabric structurally.

For best results, use ball-point scissors designed specifically for knits. Ball-point scissors (such as the Kai 5250 or Fiskars 12-73417097) feature a rounded tip that slides between fabric threads rather than slicing through them, reducing runs and fabric distortion.

Step 3: Check the Direction of Stretch

Spandex has a 4-way stretch in most athletic blends, but the degree of stretch varies by direction. The greatest stretch runs perpendicular to the selvage (cross-grain). Align the greatest stretch around the body for comfort and recovery. The least stretch runs parallel to the selvage and provides structural support.

To test: hold the fabric at opposite edges and stretch gently. The direction with more give should encircle the body horizontally. Industry standards for athletic wear (ASTM D3107) specify that waistband elastic should retain at least 90% recovery after 10 cycles of 50% stretch. Mismatched stretch direction is the primary cause of spandex shorts that sag within weeks.

Step 4: Test the Stretch Quality Before Sewing

Not all spandex behaves identically. Pre-wash the fabric or test a scrap seam before committing to the full garment. A seam stitched with incorrect settings on mismatched spandex will break after fewer than 20 wear cycles. Test by stretching a sewn seam scrap 10 times — if the stitches pop or the seam ripples, adjust the stitch length or needle before proceeding.

High-quality spandex athletic fabric typically contains 15–30% spandex by weight, blended with nylon (80/20 nylon/spandex) or polyester (74/26 polyester/spandex). Fabrics with less than 15% spandex offer poor recovery; those with more than 30% are excessively difficult to control during cutting and sewing.

Step 5: Sew with a Serger

Set the serger to a 4-thread overlock stitch. Use differential feed at 0.7–1.0 to prevent stretching or puckering. Differential feed below 0.7 causes gathering; above 1.0 causes leg elongation. Thread with polyester stretch thread (labeled “stretch” or “metallic” polyester) for the loopers and needle. Standard cotton thread breaks under repeated stretch cycles.

Use a ball-point needle sized 75/11 for lightweight spandex (under 200 gsm) or 90/14 for heavier athletic spandex (200–350 gsm). The ball-point tip slides between the elastane fibers rather than piercing them, preventing the characteristic snags and runs that occur with universal or sharp needles. Replace the needle every 8–10 hours of sewing time — a dulled ball-point needle increases skip stitches by up to 35%.

Stretch the fabric gently as you sew, allowing the machine to take up the slack. Do not pull the fabric behind the needle — let the differential feed and your gentle forward guidance do the work. Forced feeding causes seam waviness and inconsistent stitch tension.

Step 6: Sew with a Standard Sewing Machine

Equip the machine with a ball-point needle (size 75/11 or 90/14) and polyester stretch thread. Set the stitch to a narrow zigzag (width 2.5–4.0mm, length 2.5–3.0mm) or a dedicated stretch stitch if your machine includes one. Straight stitches on spandex break within the first few wears because the fabric continues to stretch after the seam is sewn.

Reduce presser foot pressure by 30–50% if your machine allows adjustment — standard pressure flattens the fabric and causes it to stretch out of shape as it feeds. Use a walking foot or even-feed foot if available to prevent layer slipping. Begin at a corner and sew toward the opposite corner, stretching the fabric gently as you advance.

Thread tension should sit at the lower end of the normal range for polyester. Over-tensioned thread creates tunnel-like puckers that persist after washing. Test on a fabric scrap before sewing the actual seams.

Summary and Key Specifications

The following table summarizes the critical settings for both machines:

Fabric composition for quality athletic spandex typically falls within 80% nylon / 20% spandex or 74% polyester / 26% spandex. Look for 4-way stretch of 50–200% depending on the blend. Elastic recovery should be 95–99% per ASTM D3107 testing standards.

Final Words

Homemade spandex shorts outperform commercial equivalents in one critical area: fit customization. When you cut and sew your own, you control every measurement. Follow the steps above precisely, use the correct needle type, and your finished shorts will retain their original dimensions through hundreds of wear-and-wash cycles.

REFERENCES:

1. Shim, E. (2018). Design of Clothing Manufacturing Processes. Elsevier Science.
2. Hearle, J. W. S., Hollick, L., & Wilson, D. K. (2001). Engineering Apparel Fabrics and Garments. Woodhead Publishing.
3. Chatr, C. & Powell, N. (2017). Advances in Apparel Production. ASTM International.
4. ASTM D3107-07(2017). Standard Test Methods for Stretch Properties of Fabrics from Warp-Knitted, Weft-Knitted, or Woven Fabrics. ASTM International.