# 5 Empirical Formula for Determination of the Coefficient of Permeability

The coefficient of **permeability of soil**(K) can also be computed from several empirical formulae, which are given below:

## 1. Jaky’s Formula

Jakey in 1944 found an empirical formula of ‘K’ for all soils; , Where is grain size (in cm) that occurs with the greatest frequency.

## 2. Allen Hazen’s Formula

, where C is a constant. The value of C is taken approximately equal to 100, when is expressed in cm.

## 3. Terzaghi’s Formula

Terzaghi (1955) developed the following formula for fairly uniform sands, which reflects the effects of grain size and void ratio.

, Where = Effective grain size.

## 4. Kozney’s Formula

, where = Specific surface of particles, = Viscosity, and = Constant( that is equal to 5 for spherical particles).

## 5. Louden’s Formula

Where a and b are constants, the value of which are 1.365 and 5.15 respectively for permeability at 10**°C**.

*Read Also:*

1. Capillarity Permeability Test

2. Coefficient of Permeability of Soil by Constant Head Permeameter