This is the measuring method i use on the jeans for my reviews.

Waist 

Pull the waistline tight so the front and back of it are as close as possible. Then place the tape measure at the edge of the waistband, and measure straight across. Multiply this measure by 2, and then you have the actual waist measurement of your jeans.

Rise

-Front rise

Take your tape measure at the crotch seam and then measure to the top of the front waistline.

-Back rise

Same method as front rise. take your tape measure and place it at the crotch seam and then measure to the top of the back waistline.

Thigh

Place your tape measure at the crotch seam and then measure in an (approx) 90-degree angle to the side

Knee

This a top sted method first start by measuring 33 cm(13 inches) down the inseam of the leg start at the crotch seam.

After measuring 33 cm (13 inches) down the inseam, then measure straight across the knee.

Inseam

Mesure from the crotch seam to the leg opening.

Leg opening

The leg opening is measured across the leg opening.