I wear a size Large and am of regular height so considering that these would go over clothes I order an extra Large....I can't even get them up to my shoulders!  I would probably need to order and 4 XL Long for these to fit...so be careful!  I'm giving these to my son who wears a medium and is 4 inches shorter then me and I'm under 6 foot!  Quality of the product is pretty good which you would expect with the price they want for coveralls!