Soil resistivity is a measure of how much the soil resists or conducts electric current. It is a critical factor in design of systems that rely on passing current through the Earth's surface. An understanding of the soil resistivity and how it varies with depth in the soil is necessary to design the grounding system in an electrical substation, or for lightning conductors.

It is needed for design of grounding (earthing) electrodes for substations and High-voltage direct current transmission systems. It was formerly important in earth-return telegraphy. It can also be a useful measure in agriculture as a proxy measurement for moisture content.