I wear a 16 or 18 in Reitmans pants...usually a 16. Because I'm oval shaped (hips and waist almost same measurements)I pretty much need an elastic waist for my pants to stay up. Because these have the front section non-elastic, I bought the 18. They fit fine when I tried them. I washed them (perfectly fine in washer on delicate and dryer on normal), and wore them and they stretched out quite a bit, so I was pulling them up. I would have been OK with a 16. I really like the fabric-it's a thicker chambray that can be worn in cooler months. Definitely recommend.