A grading curve is a useful aid to soil description. The geometric properties of a grading curve are called grading characteristics.

To obtain the grading characteristics, three points are located first on the grading curve.

D₆₀ = size at 60% finer by weight
D₃₀ = size at 30% finer by weight
D₁₀ = size at 10% finer by weight

The grading characteristics are then determined as follows:

1. Effective size = D₁₀
2. Uniformity coefficient,
3. Curvature coefficient,

Both C_uand C_c will be 1 for a single-sized soil.

C_u > 5 indicates a well-graded soil, i.e. a soil which has a distribution of particles over a wide size range.

C_c between 1 and 3 also indicates a well-graded soil.

C_u < 3 indicates a uniform soil, i.e. a soil which has a very narrow particle size range.