first off, grab a pair of your favorite jeans, a measuring tape, and find a flat surface to measure on. lay your jeans out flat, smoothing out the fabric to remove all slack.

waist

the width of the waistband, from left edge to right edge.

front rise

the length from the bottom of the crotch seam to the top edge of the front of waistband, above the button.

thigh

starting 1” below the crotch seam, the width of the leg.

leg opening

the circumference of the opening at the bottom hem.

inseam

following the inside-leg seam, the length from the crotch seam to the bottom of hem.