Every garment has its own chart, and it lives on that product's page, right under the size selector. Here is how the system works.
All measurements are in inches, taken the way we describe in How to measure. Find the row your measurements fall into: that is your size. If your waist and your hips land in different rows, follow the rule for that garment — hips for fajas, waist for waist trainers.
Size up. A faja you cannot close is a faja you will not wear, and the compression is meant to be tightened with the rows of hooks as the swelling goes down. That is exactly why the garment has three rows and not one.
Your measurements will change during recovery. Starting in one size and finishing in another is normal, which is why every closure is adjustable. Your surgeon is the one who tells you when it makes sense to change size or move to a different garment.
