Elastic Length Calculator
Calculate how long to cut your elastic for waistbands, cuffs, and casings — with seam overlap included.
Elastic Types and Stretch Ratios
Different elastic types have different stretch recoveries, which is why you cut them to different percentages of the body measurement:
Non-roll waistband elastic (the wide, ribbed type) has multiple channels that prevent rolling — it's the most comfortable for waistbands and holds its shape well at 90% stretch.
Standard woven elastic is firmer and loses some stretch with repeated washing, so cutting at 85% gives it more to work with over time.
Braided elastic narrows when stretched, which can cause it to dig in. At 80% it provides a firm hold — best used in casings rather than sewn directly to fabric.
Knit and swim elastic is the stretchiest and softest, resisting chlorine and moisture. The 75% ratio is typical for swimwear and athletic wear where a snug fit is essential.
Joining elastic: Always add 1 inch (2.5 cm) of overlap so you have enough material to lap and stitch the ends securely. For wider elastic (3/4" or 1"), you can increase the overlap to 1.5" for extra security.