Since hydraulic conductivity significantly influences the compression and deformation characteristics of granular terrains, this study examines the variations in permeability (k20) of granular soils under one-dimensional compression. Two uniformly graded calcareous soil samples were tested: one with grain sizes of 9.50-12.70 mm, and another of 4.75-9.50 mm. Both samples were subjected to one-dimensional compression and constanthead permeability tests. Key soil properties affecting permeability (k20), including absorption (n), specific surface area (Ss), relative density (Dr), void ratio (e), uniformity coefficient (Cu), effective grain size (d10), and mean grain size (d50), were analyzed. The virgin compression line (VCL) of the soil samples was identified within an oedometric stress (sigma VCL) range of 4.00-14.00 MPa, where the rate of change in soil properties affecting permeability was most pronounced. As oedometric stress increased, the instantaneous absorption (ni) of the soil samples increased linearly, with a slope (alpha n) of 0.055-0.061. Similarly, the instantaneous specific surface area (Ss,i) of the soil samples increased linearly, with a slope (alpha s) of 1.229-1.388. In addition, practical equations were developed to predict the instantaneous relative density (Dr,i), instantaneous grain size distribution curve, and instantaneous permeability (k20,i) of granular soils under one-dimensional compression.