Have the dog stand evenly on all four paws. Hurtta measures back length from the base of the neck, where it meets the shoulders, to the base of the tail; neckline around the base of the neck; and chest at its widest point, usually just behind the front legs. Compare in the chart’s units and use the same row for all three.
The Parka II page uses back length to choose a jacket size and says to choose the larger one if that measurement falls between sizes. Keep that instruction specific to this model and that situation. Hurtta’s general fit guide says not to size up “just in case.” If back length points to one row but neckline or chest points elsewhere, check with Hurtta rather than combining measurements from different rows.
The Parka II chart lists sizes 40 and 40XS with the same back-length range, 37–42 cm, but different neckline and chest ranges: 30–50 cm and 45–65 cm for size 40, versus 30–40 cm and 40–55 cm for 40XS. The shared back-length range does not make the other two ranges interchangeable.