Does polyester spandex stretch?

Yes, together, yes, spandex is specifically a stretch fabric, its why it was created to stretch and suck in like a girdle. Many polyesters do not stretch but it is often woven with other yarns or materials that give it stretching capabilities. read more

Spandex can be added to any fabric and will provide stretch. There is a loss of breathability as a trade off for the stretch, howecer. read more

A polyester stretch blend is produced by combining small amounts of Lycra or spandex, typically four or five percent, with polyester fibres. The addition of stretch to polyester garments improves comfort for the wearer by providing greater ease of movement. read more

For giving stretch to any garments made of cotton or polyester or a mix of these, Lycra (or Spandax) is used. Generally in stretchable jeans, you will find 2% to 7% Lycra (and you will see the difference in stretch for sure as percentage of Lycra increases). read more