Enter the diameter at the 60th percentile and the diameter at the 10th percentile into the calculator to determine the coefficient of uniformity.

Coefficient Of Uniformity Calculator

Enter D10 and D60 (in mm) — add D30 for Cc and gradation.

Cu (quick)
Cu + Cc + Class

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Coefficient Of Uniformity Formula

The following formula is used to calculate the coefficient of uniformity for a given set of diameters. 

CU = D_{60} / D_{10}

Variables:

  • CU is the coefficient of uniformity
  • D60 is the diameter at the 60th percentile
  • D10 is the diameter at the 10th percentile

To calculate the coefficient of uniformity, divide the diameter at the 60th percentile by the diameter at the 10th percentile. This ratio provides a measure of the uniformity of the particle sizes in a given sample.

What is the Coefficient Of Uniformity?

The coefficient of uniformity (CU) is a measure used in soil mechanics and sedimentology to describe the uniformity of particle sizes in a given sample. It is calculated as the ratio of the diameter at the 60th percentile (D60) to the diameter at the 10th percentile (D10). A higher CU value indicates a wider range of particle sizes, while a lower CU value indicates a more uniform particle size distribution. This measure is important in various engineering applications, such as determining the suitability of soil for construction projects and assessing the stability of slopes and embankments.

How to Calculate Coefficient Of Uniformity?

The following steps outline how to calculate the Coefficient Of Uniformity.

  1. First, determine the diameter at the 60th percentile (D60).
  2. Next, determine the diameter at the 10th percentile (D10).
  3. Next, calculate the coefficient of uniformity using the formula CU = D60 / D10.
  4. Finally, calculate the Coefficient Of Uniformity.
  5. After inserting the values and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Diameter at 60th Percentile (D60) = 0.6 mm

Diameter at 10th Percentile (D10) = 0.2 mm