Why do bras stretch out?

Bras stretch out primarily due to the natural degradation of elastic fibers, specifically the elastane (spandex) components that provide the garment's ability to snap back into shape. Heat, humidity from sweat, UV exposure, and certain laundry chemicals progressively break down the polymer chains in these elastic fibers, reducing their recovery power over time. Daily wear creates what scientists call 'viscoelastic creep' - the bands and straps gradually elongate under constant tension, which accelerates when you wear the same bra consecutive days without allowing the elastics recovery time.

Your laundering choices significantly impact this process, as dryer heat, chlorine bleach, and fabric softeners particularly damage elastane fibers, while cold water washing and air-drying preserve their engineered support properties. Additionally, fit plays a critical role — bras that start on the tightest hook or bands that are too small over-stress the elastic components from day one, dramatically shortening their supportive lifespan.