A pant's "rise" refers to the measurement between the crotch of the pants and its top. However, due to the curvature involved, rise cannot always be deduced from the inseam and outseam measurements. Usually, the back and front rises of a pair of pants will not be equal, to accommodate the natural shape of a person's body. With a little methodology and a good measuring tape, you can find accurate rise measurements easily, for use in custom clothes creation, tailoring or your next trouser fitting.
Measure a Pant's Rise
Iron the pants you want to measure. Eliminate bends and curls in the fabric, which can make pants difficult to accurately measure.
Lay your pants flat on a table.
Find the front rise of the pants. Measure the distance between the crotch seam and the top of the waistband in the front. Make sure that you measure in a straight line, directly up the zipper.
Wear the pants and sit in a chair. Make sure to tug the pants down before sitting to achieve an accurate measurement.
Find the back rise of the pants. Have a friend measure the length between the top of the pant's waistband and the place at which your body meets the chair in a straight, vertical line.