The purpose of body armor is to cover the vital organs in your chest cavity. You don't want it too low where your duty belt pushes it up, as this will crease the vest over time, and make it less effective. About 2 inches is recommended. If you go to the manufacturers website, or look in a police supply catalog, they will give the the areas that need to be measured. You may want to stop by a local tailor, or better yet, a local police supply company to make sure the measurements are accurate.