I run between a size 16 and size 18 in 1950's pattern sizes (34-26-37 to 36-28-39, basically), and I can do it without the 1950's Girdle that Ate Chicago, too. Sadly, modern clothes are not made for that kind of measurement ratio and I basically had to stop wearing pants because none of them fit both at the waist and the hips. This says Bettie Page was 36-23-35. Why, oh, why did curves go out of style??
Oddly, I'm not sure what size I am in modern clothes--I just wear what fits and ignore the number.