Granular material can range from very small colloidal particles, through clay, silt, sand, gravel, and cobbles, to boulders.

Size ranges define limits of classes that are given names in the Wentworth scale (or Udden–Wentworth scale named after geologists Chester K. Wentworth and Johan A. Udden) used in the United States.

The Krumbein phi (φ) scale, a modification of the Wentworth scale created by W. C. Krumbein[1] in 1934, is a logarithmic scale computed by the equation where This equation can be rearranged to find diameter using φ: In some schemes, gravel is anything larger than sand (comprising granule, pebble, cobble, and boulder in the table above).

A sediment deposit can undergo sorting when a particle size range is removed by an agency such as a river or the wind.

The sorting can be quantified using the Inclusive Graphic Standard Deviation:[4] where The result of this can be described using the following terms: