Classical graphics and regression procedures have been used to estimate preconsolidation pressure (σ p) from soil compression curves, but none of these procedures is easy to use and they often involve subjective judgement. This paper presents a simple procedure for estimating σ p from uniaxial compression tests for either saturated or unsaturated soil conditions. We evaluated five methods for estimating σ p from standard soil compression curves for an applied stress sequence of 25, 50, 100, 200, 400, 800, and 1600 kPa. Four methods estimated σ p as the intersection of two lines: (a) the regression line obtained for the first two, three, four or five points of the applied stress sequence in the secondary compression portion of the compression curve and (b) the extension of the virgin compression line determined from the points associated with applied stress of 800 and 1600 kPa. Method 5 consisted of the Schmertmann method. The σ p determined for each method was compared to σ p estimated using the graphical procedure of Casagrande for 288 soil compression curves from three soils in Michigan and from values reported in the literature. Methods 1 and 5 fit our data best at low σ p (high soil water content) while methods 2 and 3 fit the data better at high σ p (low soil water content). Based on a low RMSE (18), a high R 2 (0.92), and closeness of fit to the 1:1 line, a combination of methods 1 and 3 was selected as the best estimation procedure. For data from the literature, methods 1 and 2 provided the best estimate based on lowest RMSE of 5 to 9, R 2 of 0.98 to 0.99, and the closest fit to the 1:1 line. The combined methods were not tested for published data since matric potentials for measured values were unknown. The final procedure, combined methods 1 and 3, was programmed into a computer spreadsheet provided in an Appendix. This procedure provides a fast and reliable estimation of σ p for saturated and unsaturated soil conditions and eliminates subjective judgment associated with classical graphical procedures.