Definitely size down! I am plus size 18-20 and measure around 122cm around bust - it was extremely stretchy the XL and I would repurchase L in future to have the slightly tighter/more compressive fit, which surprises me as I normally wouldn't fit an XL item at this size, let alone a Large! The fabric is soooo soft and beautiful - it doesn't smell with sweat which was a concern i had initially as I normally stick to cotton based stuff. Really well made, really awesome label design which allows you to remove it really quickly without using scissors or ripping the item. Really happy with the customer service, really fast responses - a wonderful reliable brand!