164 cm (vampire form)
Eventually, it is revealed that Yuuki was born a pureblood vampire, a member of the Kuran Clan. Her mother had sacrificed herself to seal Yuuki’s vampire side, as well as her memories. Yuuki’s existence was hidden from the other vampires. She was kept in a basement in the Kuran Mansion without any windows in order to protect her from both her parent’s older brother, Kuran Rido. It was when he attacked the Kuran family, seeking to take Yuuki, when her memories and her Vampire side were sealed.
This also makes her Kaname’s sister, and his intended fiancee, meaning Yuuki was born to be his wife.