In my own meditation practice, I experience the lower dan tian as being in the area of the navel, but a bit lower than the navel (viewing the front of the body when a person is upright) and inside a ways. From what I have encountered from different references, various people place it in this general area but the exact location given can vary by an inch or two or so depending on the source.     The following excerpt from "Opening the Dragon Gate" may shed some light on why this is:   Excerpt from "Opening the Dragon Gate", Chapter 7, page 89. "Taoists regard Earth as a universe, and they regard the human body as a universe. Just as the Earth has longitudinal meridians and latitudinal parallels, the human body also has longitudinal meridians and latitudinal parallels. The question of "acupuncture points" on the Earth's meridians has already been raised; this is in itself a major breakthrough in the domain of theory. The Chinese theory and application of longitudinal meridians in the human body are known to the whole world, but the theory and practice of the latitudes of the human body has long been held secret by Taoists, completely unknown to the world.   When we first visited Master Wang Liping, he told us about the existence of the latitudes of the human body. The phenomenon is sure to provoke the interest and attention of people all over the world., and inquiries into the mysteries of the human body should make a major advance.   Earth has a central line, which is the equator; the human body also has a central line. Taoists divide the human body into three elixir-producing segments, which are the upper, middle, and lower elixir fields everyone talks about. People who do meditation exercises generally know the lower elixir field is in the lower abdomen, below the naval, but they cannot accurately determine the precise location. Taoist practitioners over the ages have also given many different explanations of this point. The conclusion at which Master Wang Liping has arrived through his own personal experience in training is that the exact location of the lower elixir field in the human body varies according to the geographical location of the individual. In Chinese people, it is between 1.2 and 1.5 inches below the navel; in people who live nearer to the equator, the lower elixir field is closer to the navel; while in people who live farther away from the equator, the lower elixir field is further from the navel. "