Some ostomy belts adjust more than others, which is why each size specifies the range it is suitable for. Contrary to popular belief, you will not need your waist measurement to properly size an ostomy belt. Instead, using a pliable tape measure, you should measure around the body at the stoma level, while lying on your back. If you are going for a wider ostomy bag belt, measure just above and below the stoma and average the two measurements. If you find yourself in-between sizes, you can either go down a size for a tight fit or up for a looser one. Some ostomy support belts are tailored to work with the ostomy bag you are using, hence you should also check the flange diameter, which is either 2 3/8" or 2 3/4", and whether they are intended for the left or the right side of the body.