The aim of this study was to investigate the effects of initial values of soil mean grain size (d500) and soil uniformity coefficient (Cu0) on the one-dimensional compression behavior of granular soils. Soil samples consisting of equant-shaped, calcerous origin, crushed individual grains with a grain size range of 2.00–25.00 mm were examined in the laboratory tests. The yield stress, the initial and final stresses of the virgin compression line (VCL), and the hardening stress of soil samples during one-dimensional compression behavior were determined. Results indicated that an increase in the soil’s initial mean grain size and a decrease in the soil’s initial uniformity coefficient led to an increase in the value of these oedometric stresses. Soil samples reached the virgin compression line at an axial deformation (εa(VCL-i)) of 10–13% and passed this line at an axial deformation (εa(VCL-f)) of 26–30%. It was observed that the instantaneous index void ratio values (eminiandemaxi) of the soil samples decreased linearly with a slope (αe) of 0.10 in the e- ln σV plane during one-dimensional compression. The curve of the soil’s instantaneous minimum void ratio (emini) values during one-dimensional compression was proposed as a lower boundary for the one-dimensional compression curve of granular soils.