As a sewing blogger I am very aware of the problems involved in fitting garments made from Big 4 pattern company patterns: Simplicity/New Look, Vogue, McCall's, and Butterick.* It's well known among us sewists (see recent posts from Shams and Robin) that if you go by your actual body measurements you will most likely end up with an oversized garment. This is because these pattern makers are notorious for ridiculous amounts of ease in their patterns.
A typical sewing pattern includes both wearing and design ease. Wearing ease is minimal and exists so that one can actually sit, stretch, and move in a garment. Design ease is what makes the difference between a dress skimming the body's curves or billowing around them. Design ease is calculated by the designer/maker of the pattern to give the finished garment a specific look. However, it seems the Big 4 likes to overcompensate on the wearing ease issue. I can only guess it's to allow for more women to fit into each size? Why that is, don't ask me.
Close fitting = 0-3"
Fitted = 3-4"
Semi-fitted = 4-5"
Loose fitting = 5-8"
Very loose fitting = 8" and more of ridiculous ease!
Close fitting = 0-2"
Fitted = 2-3"
Semi-fitted = 3-4"
Loose fitting = 4-6"
Very loose fitting = 6" and more