Wrap the measuring tape around your hips where you would like the trunks to sit.
Wrap the measuring tape around the largest part of your bum
Crotch Rise (front view)
Place the tape at the top of your waistband where you want the trunks to sit on your lower abdomen.
Crotch Rise (back view)
Mens Measurement Guide
Run the tape between your legs to the top of the waist band in the back/ bum crack.
This measurement is typically 19-24 inches.