The configuration of the tail plasma sheet in earth's magnetotail has been calculated in connection with a three-dimensional magnetospheric B field modle. This model is based on the idea that thermal plasma, tail currents, and magnetic field be in magnetohydrostatic equilibrium during time periods of magnetically quiet conditions. The tail configuration is generated by a separation method assuming a cylindrical magnetotail boundary with constant radius. The separation method restricts self-consistency to planes perpendicular to the tail axis. The computed tail plasma sheet is flexible and reacts to changes of the earth's dipole tilt angle and changes of the solar wind pressure. Consequences for the plasma sheet configuration with respect to the assumed tail magnetopause shape and the separation method are the following: (1) the plasma sheet thickness increases in YGSM direction toward the flanks of the tail; (2) the plasma sheet becomes thicker and more diffuse with increasing distance from the earth; (3) during the northern hemisphere summer, the neutral sheet is raised above the magnetospheric equatorial plane around local midnight but crosses this plane and is depressed below it near the flanks of the tail. The latter result agrees qualitatively with Fairfield's empirical neutral sheet model which he derived from spacecraft measurements of the tail field polarity. This agreement between theory and observational material provides a further piece of evidence that the magnetohydrostatic theory is an appropriate level for describing quantitatively the quiet state of the magnetosphere.