Tortuosity is a property of curve being tortuous (twisted; having many turns). There have been several attempts to quantify this property.

Tortuosity is commonly used to describe diffusion in porous media, such as soils and snow.

Subjective estimation (sometimes aided by optometric grading scales) is often used.

The simplest mathematical method to estimate tortuosity in 2D is shown here.

Arc-chord ratio equals 1 for a straight line and is infinite for a circle.

Related formulas


τtortuosity (dimensionless)
Llength of the curve (m)
Cdistance between the ends of the curve (m)