The best way to ensure accurate sizing is to measure a garment which already fits the wearer comfortably and use this measurement to determine the best size. This is done by laying the garment flat on a flat surface. The garment is then measured across the front, side-seam to side-seam, from just a few centimetres below where the sleeve joins the body of the garment. Then you can compare this to the sizing guide to see what would be suitable. If you’re between sizes, always size up.