Supreme has changed the sizes of their t-shirts, t-shirts that are from fall/winter 2017 season thereafter fits bigger. Below is a chart of the new t-shirt size measurements. Please note that this sizing measurement is only applicable to the normal supreme cotton printed graphics tees, which are under the "t-shirt" category on Supreme website. For t-shirts that are under the "tops" category (typically pocket tees, small box logo tees etc.) please do not use this sizing chart.
Below is the sizing chart. For tees that are produced before FW17, refer to the last diagram for size measurements.
Tees before FW17:
I do not have the measurements for size S and XL tees. If anyone happen to own the tees it would be great if you can help to make a measurement and comment below so I can update this chart.