Only worn a sparingly around the house as a cozy sweater. It’s so breathable and temperature adjustable that it can be worn in winter or cool summer nights. Check out their size chart on Icebreakers website. I normally wear an XS in their shirts and a S allows for light layers. https://www.icebreaker.com/en-us/womens-knitwear/merino-waypoint-crewe-sweater/104316U2.html?dwvar_104316U2_color=329&dwvar_104316U2_US=in_line Merino is super lightweight, soft, non-itchy, non-clammy, warm in the cold and cool in the heat, and has a miraculous ability to resist odour. Because it was made in the mountains rather than in a petrochemical laboratory. Merino wool fibre is naturally renewable, recyclable and biodegradable*.