British Military FR Desert Thermal Undershirt

Measure around the fullest part of your chest while wearing light clothing. These are wearer body measurements, not the garment’s flat width. Letter sizes are approximate MPO equivalents; use the original military size and product fit notes first. Inch values are converted from centimetres and rounded to one decimal place. If your measurement falls between the listed ranges, check the product’s exact size and fit notes.

Choose height separately from chest size

Military upper-body size = wearer height / wearer chest, in centimetres. Small, Medium, Large and XL describe approximate chest size only. They do not specify height. Two jackets can both be Medium but have different lengths for different wearer heights.

Feet/inches are rounded to the nearest inch. These are label height codes, not fixed height ranges. Check both your height and chest against the selected garment, and follow its fit notes.

Example: 160/96 and 170/96 both indicate a 96 cm (37.8 in) wearer chest — approximately Medium in this guide. The 160/96 is for a 160 cm wearer (about 5 ft 3 in); the 170/96 is for a 170 cm wearer (about 5 ft 7 in).

Reading a military size: On an upper-body label such as 190/110, 190 is wearer height in centimetres (about 6 ft 3 in) and 110 is wearer chest circumference (43.3 in; approximately Large in this guide). For garment measurements, pit-to-pit is the flat width across the chest; twice that width gives the garment circumference, not the wearer’s chest size.

View the full UK/US Sizing Guide