The sizing of Barbour’s clothing is divided into three segments:
Heritage: Slim fit. Order one size up for a close fit and 2 sizes up for a larger fit.
Contemporary: A fitted cut. Order regular size, but expect a lean and close fit.
Classic: An active cut for comfort in the field with a traditional fuller cut.
In the case of Barbour outerwear, sizing takes into account the appropriate layers beneath. That means you do not need to order a size up for a comfortable fit.