# Uniformity Coefficient

Uniformity coefficient, abbreviated as \(C_u\), also called coefficient of uniformity, a dimensionless number, classifies a soil as well graded or poorly graded. For the soil to be well graded for a given sample, the range must be between greater than 4 to 6. If less than 4 it is classified as poorly graded.

## Uniformity Coefficient formula

\(\large{ C_u = \frac{ D_{60} }{ D_{10} } }\) |

### Where:

Units |
English |
Metric |

\(\large{ C_u } \) = uniformity coefficient | \(\large{dimensionless}\) | |

\(\large{ D_{10} } \) = is the sieve diameter (grain size) which there are 10% of particles go through. | \(\large{in}\) | \(\large{mm}\) |

\(\large{ D_{60} } \) = is the sieve diameter (grain size) which there are 60% of particles go through. | \(\large{in}\) | \(\large{mm}\) |

Tags: Coefficient Equations Soil Equations Geotechnical Equations