A theory is presented to calculate hydraulic conductivity from successive measurements of water content profiles for soil in situ. With unsaturated soil, potential gradients are inferred using moisture characteristics, but with saturated soil these gradients must be measured directly. The weight of overburden can affect in situ soil water suction, and a method for determining this effect is given. The theory was applied to a soil profile with marked changes in moisture characteristics and texture, and conductivity was determined for several depths as a function of water content.