The HOLLOW to HEM measurement was always a term that confused me, and is also excessively important, given that I'm a tall bride. It'll also help you guys out, in determining how long your dress should be.
HOLLOW TO HEM is a standard industry term. Start the tape at the hollow at the base of your neck and measure down to where you want the hem. If your skirt will be full, be sure to measure out at an angle to allow for the fullness. Also, be sure you?re wearing the same height heel you'll wear on your wedding day.