The waist measurement... ok let's start with a "no don't do it like that"...there enough said.
This is the correct way to measure the waist fold the waistband about 4'/8cm away from the fly... this will give you the true measurement, then measure between the edges at the top of the waistband.
The inside leg or inseam is measured from the top of the seam at the crotch to the bottom of the hem.
The hem or opening is measured across the bottom of the leg... the diameter is the measurement from side seam to the other side don't measure from seam to seam as the front panel is always smaller. Just pull the opening tight, flatten and measure from side to side.
The knee measurement is taken from approximately 35cm from the crotch seam, fold the jean flat and measure from side to side.
The back rise is measured from the crotch to the bottom of the waistband.
The rise is measured from the crotch to the bottom of the waistband.