Most of our fits run alpha sizes, S through 3XL. A few pairs stop at XL or 2XL; the range for each fit sits on its listing.
Take a pair of trousers that fits you well, lay it flat, and measure the waistband straight across. Double that number: that is your waist in inches. Match it against the chart on the listing you are looking at. Do not measure your body over clothes and do not measure the thigh; on a baggy cut the thigh number tells you nothing.
Round down. The cut carries so much built-in room that the smaller waist with the same wide leg almost always sits better than the bigger waist sliding down.
Inseams run long on purpose; the hem is supposed to stack on the shoe. If you are shorter than about 5'7", plan on one cuff. There is a full fit guide in the zine with the details.