Since the textural classification is based on the percentages of sand, silt, and clay size making up the soil. Such a classification is more suitable for describing coarse-grained soil.

Since properties of clay soils is less dependent on particle size distrubution(textural classification) and more dependent on size it is best suited for clay soil.

For general engineering purposes, soil can be classified in terms of particle size, textural and unified soil.

Based on particle size, soil can be classified as

Group index of soil usually varies by

In the particle soil classification system, soils are arranged to the grain size.

Terms such as gravel, sand, silt, and clay are used to indicate grain sizes. These terms are used only as a designation of particle size.

Highway research board classification system is also known as public road administration (PRA) system.

HRB classification system, also known as public road administration (PRA) is based on both the particle-size composition and plasticity characteristics.

Indian standard classification (IS: 1948-1970) is based on the M.I.T. system.