Students really like this suit
It seems to fit well and be effective for the individuals wearing it.
*GSM = Grams per square metre
Assuming you are of average build. For example if you are 180cm tall, get a size 180; if you are 181cm, get a size 190.
What build are you? If you have a heavy build, large shoulders, bust and/or waistline, go +1 in the sizing (you may have to shorten the sleeves and pant legs). Its OK if the ties do not pull shut completely. Alternatively if you are very thin (especially in the shoulders), you may need to go -1 in the sizing.
How much should I allow for shrinkage? Generally poly-cotton with shrink 3-5%, and cotton/canvas will shrink 5-10%. The uniform will feel slightly oversized when you wear it for the first few times.