As described in the FAQ, these authentic soccer jerseys are produced in Asia, mainly for Asian soccer players. Consequently, the sizing is significantly slimmer than your usual US sizes. To help you find a comfortable fit, use the conversion charts above: select your usual size in the Mainstream Scale and find the corresponding PHOOTYKITS size.
The chest dimensions in inches are also indicated in case you want to take a tape-measure to your torso, but as a general rule, if you want a looser fit, SIZE UP! And if in doubt, SIZE UP!