This paper models the transverse “runout” of a flexible, nonflat, spinning disk. Analysis is provided to compute the deflection that a warped or skewed disk will take after spinning. This is a problem of importance in magnetic and optical recording, for which spacing and/or contact with the recording head must be precisely controlled. The effect of disk nonflatness appears as an equivalent pressure load in an analogous formulation for a flat plate. Results are presented for various freely spinning disks. Comparisons to experiments show the range of the models predictive capability.Presented as a Society of Tribologists and Lubrication Engineers paper at the ASME/STLE Tribology Conference in Toronto, Ontario, Canada, October 8–10, 1990