My chest and my arm length are two very different sizes. Which size shirt should I choose?

Your best bet is to choose the shirt size that corresponds to the measured circumference of your chest. For example, size 3XL corresponds to a chest circumference of 118 cm. Your arms will fit that shirt correctly if they’reeach 80 cm long. Please note, always measure arm length from your neck to the end of your wrist (this measurement should correspond to the desired length of your sleeves).