How is thermal conductivity calculated?

The formula for calculating thermal conductivity is heat multiplied by the distance divided by the product of surface area times the temperature gradient. NDT Resource Center explains that thermal conductivity is the property of a material to conduct heat. Increased thermal conductivity means a higher rate of heat transfer.

Heat, represented as Q, is transmitted through a unit of distance, or L. Q multiplied by L acts as the numerator in the thermal conductivity equation. The unit of surface area, or A, is multiplied by a unit of temperature change, or Delta T. A multiplied by Delta T acts as the denominator for the equation. A and Delta T must be expressed in the same unit of measurement.