People's sizes vary in two different way: height and width. Austrians have a distinctive size system for both jackets and trousers. Regarding jackets, chest width is in centimeters and length in Roman numerals. These are measurements of the person, not the garment!
Width
Easy size
Our recommendation
Austrian system
X-Small
76-84 cm
80-84 cm
Small
84-92 cm
88-92 cm
Medium
92-100 cm
96-100 cm
Large
100-108 cm
104-108 cm
X-Large
108-116 cm
112-116 cm
2X-Large
116-124 cm
120-124 cm
3X-Large
124-132 cm
128-132 cm
Width is measured from the widest part of the chest. This is easily achieved with measuring tape. Overcoats have already some extra in size to accommodate clothing worn under them, so do not order a bigger size "just in case". Without exception, that leads to too big clothing not fitting properly.
Length
Easy size
Our recommendation
Austrian system
Short
163-171 cm
I-II
Regular
171-179 cm
III-IV
Long
179-187 cm
V-VI
X-Long
187-195 cm
VII-VIII
Instructions for choosing width also applies for length.
Excellent shirt! Very well made, outdoors proof rip-stop material. Two huge pockets, at least 20x25cm. Magnificent overall. Has become my new go-to camping, hiking, outdoors shirt.
I'm 183cm tall and have a 104cm chest circumference. Usually wear M or S. 170/96 size fits great for a loose fit but not huge baggy fit.