The size of a harness is determined by the size of the waistbelt and leg loops.
For every harness size, the range of adjustment options indicated for the waistbelt corresponds to positioning on the hips, with equipment loops placed evenly on both sides, along the thighs (see diagram).
The adjustable harness models have sizes whose waistbelt adjustment options overlap. For users of non-adjustable harnesses whose waist size is between two sizes, it is best to choose the larger of the two harnesses. The harnesses have an additional tightening range, from 3 to 4 cm, depending on size. This option allows the harness to be correctly secured.
Some Petzl harnesses have adjustable leg loops. These also allow them to better adapt to different body shapes.