New with tags women's Nike Therma-FIT Swift Women's Running Vest Size Small. While laying flat and zipped, the armpit to armpit measurement is approximately 20.25" and the shoulder to waist is 21.5" (the jacket is slightly longer in the back - see photo). This product description on the Nike website (https://www.nike.com/t/therma-fit-swift-womens-running-vest-VRPfb1/FB7537-010?nikemt=true&cp=29437596259_search_--x-20404158439---c-1012445335-00196608720430&dplnk=member&gad_source=1&gclid=Cj0KCQjwxsm3BhDrARIsAMtVz6M2qPpsfozNUh3xKJ7xaXKc77deGZFdIf8Nue5uDdt7Xvwelv7cxusaAgmIEALw_wcB&gclsrc=aw.ds) is as follows: If you're debating whether it's too chilly or breezy to go for a run, take that first step out the door in this vest. With heat-regulating tech, you won't be fighting the cold alone. Plus, the loose fit makes for easy layering, so before, during and after your run, you're set to take on cold-weather conditions.