Having trouble adjusting neckline

Hi! I love the way my chai Tee fits, but I'd like a higher neckline so that I get less sun on my chest (I've had too much sun over the years). I am trying to adjust the neckline on the pattern, and I have tried to measure the ratio of the neckband to the neckline in order to cut the neckband to the correct length. However, I keep calculating that the neckband is actually LONGER than the actual neckline. Is this correct? I thought neckbands were always smaller so that you needed to stretch them. Am I thinking about this all wrong? Thanks for any suggestions. Kathy