Formula for thermal conductivity

$$\frac{Q}{t} = -k A \frac{dT}{dx}$$

Where:

• $Q/t$ is the rate of heat transfer (in Watts, W)
• $k$ is the thermal conductivity (in W/(m·K))
• $A$ is the cross-sectional area through which heat is flowing (in m²)
• $dT/dx$ is the temperature gradient (in K/m)

Rearranging to solve for thermal conductivity ($k$):

$$k = -\frac{Q}{t} \frac{1}{A} \frac{dx}{dT}$$