I believe this is a size 6-8. Armpit to armpit measures 18” or 36” all around. I’m going to list this as a size 6 since it’s supposed to be wear slightly loose. Be aware of the measurement before buying In excellent pre owned condition, no tears no stains no pilling Layer on this soft, lightweight long sleeve when you want cozy coverage with a feminine look. Wear it for warm-ups, cool-downs, or yin yoga classes. Made with lightweight, buttery-soft Nulu™ fabric that's sweat-wicking and four-way stretch. nulu™ Lightweight, buttery-soft Nulu™ fabric wicks sweat and is four-way stretch buttery-soft handfeel lightweight sweat-wicking four-way stretch features Designed for: Yoga Lycra®: Added Lycra® fibre for stretch and shape retention Relaxed fit, hip length: Layers easily and gives you room to breathe