Our sizing is based around average, reasonably fit people. It should match the size you'd choose on the high street, not a cycling racing brand. Brands tend to have wildly varying size policies. Ours is "real".

 

CHEST INCHES CHEST CM
XS 30-32" 76-81cm
S 32-34" 81-86cm
M 34-36" 86-91cm
L 36-38" 91-96cm
XL 38-40" 96-101cm

 

Our tops have a "casual fitted" cut. They're looser, but more fitted than non-cycling fashion tops.
CHEST:
Measure around the fullest part of your chest, keep the tape level, under your arms and breathe naturally. Don't tense!