New with tag 'Marks & Spencer' black 'Straight' trousers

Size 18 Medium   
Waist 38"
Rise 12"
Inside leg 30"  
Across the hem 9"

To check your inside leg length please lie trousers flat & measure from the crotch to the hem

To check the waist size on trousers you already have please lie them flat, don't bring the front of the waist up to match the back of the waist
Lie them flat & measure across the very top inside the waistband that is & double the measurement to get your waist measurement
Please keep in mind different styles of trousers sit differently & the rise makes a difference too