Degree of Saturation Calculator
Calculate degree saturation with our free science calculator. Uses standard scientific formulas with unit conversions and explanations.
Reviewed by Daniel Agrici, Founder & Lead Developer
Formula
S = (w * Gs) / e; n = e / (1 + e)
This Degree of Saturation Calculator computes results from your provided inputs using the calculator's underlying model.
Frequently Asked Questions
What is the degree of saturation of soil?
The degree of saturation (S) is the ratio of the volume of water to the volume of voids in a soil mass, expressed as a percentage. A fully saturated soil has S = 100%, meaning all void spaces are filled with water. A completely dry soil has S = 0%. The formula is S = w * Gs / e, where w is gravimetric water content (as a decimal), Gs is specific gravity of solids, and e is the void ratio. This parameter is critical for determining soil behavior, particularly in fine-grained soils where saturation level affects strength and compressibility.
How does degree of saturation affect soil behavior?
The degree of saturation profoundly influences soil mechanical behavior. In unsaturated soils, negative pore water pressure (matric suction) exists at the air-water interface within pores, providing apparent cohesion that increases shear strength. As saturation increases toward 100%, this suction decreases and effective stress drops, potentially leading to reduced bearing capacity and increased settlement. In slopes, rising saturation from rainfall infiltration is one of the primary triggers for landslides because it reduces shear strength while increasing the weight of the soil mass.
Can the degree of saturation exceed 100%?
Physically, the degree of saturation cannot exceed 100% since voids cannot hold more water than their total volume. However, calculated values slightly above 100% can occur due to measurement errors in water content, void ratio, or specific gravity determinations. If your calculated S exceeds 100%, check your input parameters for accuracy. Common sources of error include incorrect specific gravity assumptions, volume measurement errors in the void ratio test, or water loss during sample handling.
References
Reviewed by Daniel Agrici, Founder & Lead Developer · Editorial policy